Local personnel are working two of the West’s most destructive current incidents under a mutual aid pact signed in 1950

Pasadena firefighters have spent the past several weeks working wildfires in three states, including two of the most destructive incidents burning in the West, as the region moves into the heart of its fire season.

Pasadena Fire Department personnel have been assigned to major incidents across California, Oregon and Washington, according to Fire Chief Chad Augustin. Water Tender 34 spent four days on the Summit Incident, and a fire engineer served seven days on the Biscar Incident as a fireline paramedic. A captain worked the Fox Incident as a medical unit leader before being reassigned to the Old Trails Fire in Spokane. A firefighter deployed to the Grasshopper Incident as a comp claim unit leader, and another was sent to the Gann Incident in Calaveras County.

Those last two assignments put Pasadena crews on fires that have destroyed hundreds of buildings. The Old Trails Fire broke out Aug. 1 west of Spokane and, together with the neighboring Fairview and Autumn Lane fires, is now managed as the Spokane Complex. Spokane County Fire District 3 Chief Cody Rohrbach said 640 of the more than 700 structures lost in the complex burned in the Old Trails Fire alone. Roughly 65,000 people were placed under evacuation orders. Spokane Mayor Lisa Brown called it “the worst natural disaster our region has faced.”

The Gann Fire ignited Aug. 3 near Hogan Dam Road and Gann Road outside Valley Springs in Calaveras County and had burned 10,372 acres with 19% containment as of the evening of Aug. 5, according to the California Department of Forestry and Fire Protection. Seven structures have been destroyed and one firefighter injured. A department spokesperson, Ricardo Coronado, described the terrain there as “steep and rugged.” Investigators arrested a 65-year-old Valley Springs man, alleging he recklessly started the fire while operating spark-producing equipment in vegetation.

Governor Gavin Newsom secured a Federal Emergency Management Agency grant for the Gann Fire covering 75% of eligible suppression costs, the state’s third such grant of 2026, according to the Governor’s Office of Emergency Services.

The legal architecture behind these deployments is 76 years old. The California Disaster and Civil Defense Master Mutual Aid Agreement, signed in November 1950 by Governor Earl Warren, commits the state and its cities and counties to share firefighting, police, medical and communications resources during disasters. Under the state mutual aid plan, a local agency is expected to have reasonably exhausted its own resources before outside help is ordered.

Pasadena does not absorb the full cost of sending crews. The California Fire Assistance Agreement is the negotiated reimbursement mechanism for local government fire agencies responding through the state mutual aid system, and the Governor’s Office of Emergency Services processes those claims through its Mutual Aid Reimbursement System.

Washington is having its worst fire year since 2021, with more than 1,000 fires burning about 425,000 acres during a fourth consecutive statewide drought, according to the state Department of Natural Resources. Fire season in both states typically runs June through October, leaving roughly two months of peak exposure ahead.

Closer to home, Pasadena voters will decide Nov. 3 whether to approve a dedicated parcel tax for the fire department that would pay for year-round brush clearance and wildfire prevention among other work.

This week’s slight cooldown will be short-lived, with forecasters warning Tuesday that widespread dangerous heat is expected to return to the Southland by the weekend.

While temperatures are expected to ease by a couple of degrees Tuesday through Thursday, the National Weather Service said residents should use the break to prepare for another prolonged stretch of triple-digit heat beginning Friday.

“Have a plan to stay cool, especially if work or other activities take you outside mid-morning to mid-evening hours or do not have access to air conditioning,” the NWS said.

Widespread moderate to high heat risk is expected Friday through the weekend, when temperatures are forecast to climb into the mid-90s to 105 degrees across most inland communities.

In the western San Gabriel Mountains and the 5 and 14 Freeway corridors, a heat advisory will take effect at 10 a.m. Thursday, with triple- digit temperatures anticipated, but it will be replaced by a more severe extreme heat warning at 10 a.m. Friday through 8 p.m. Sunday, when highs are expected to range between 95 and 105 degrees.

“Now is the time to start socializing this threat with your community and family and consider rescheduling activities that might but you or your loved ones at risk,” according to an NWS statement. “Have a plan to stay cool, especially if work or other activities take you outside mid-morning to mid-evening hours or do not have access to air conditioning.”

The weather service also warned that hot, unstable conditions and pockets of gusty winds could elevate the risk of large wildfires heading into the weekend.

The agency that serves Pasadena and Altadena is deploying non-biting males carrying Wolbachia bacteria to curb disease-spreading Aedes aegypti

The mosquito-control agency that protects Pasadena, Altadena and two dozen other San Gabriel Valley communities began releasing tens of thousands of non-biting male mosquitoes last week in the community of Bassett, launching a new effort to shrink the population of an invasive species that can spread dengue, Zika and chikungunya.

The program, called SGV Mosquito Match, is the San Gabriel Valley Mosquito and Vector Control District’s first use of the sterile insect technique against Aedes aegypti.

The district said it will release more than 30,000 male mosquitoes a week from cardboard tubes within a 25-acre section of Bassett for 16 weeks, from July through October. The males carry Wolbachia, a naturally occurring bacterium that, according to the district, makes them unable to produce viable offspring when they mate with wild females — a mismatch the district says will gradually reduce the biting population.

Releases began in an area bounded by East Temple Avenue, Millbury Avenue, Moccasin Street and Vineland Avenue. The district said it chose the unincorporated neighborhood, north of Avocado Heights, because years of surveillance found high numbers of Aedes aegypti there.

The program is run by the same district that serves more than 1.5 million residents across 26 cities and unincorporated areas, including Pasadena and Altadena, and that led the operation to treat thousands of neglected swimming pools in the Eaton Fire burn area last year. The district tests mosquitoes across the valley for viruses including West Nile and evaluates the risk of dengue, Zika and chikungunya.

“As the Aedes aegypti population expands throughout the San Gabriel Valley, the risk for local transmission of dengue, Zika and chikungunya also increases,” District Manager Jason Farned said in a statement. He said the technique “utilizes mosquitoes of the same species to work for us, not against us.”

The mosquitoes are EPA-approved WB1 males reared by the company MosquitoMate, using a Wolbachia strain the U.S. Environmental Protection Agency registered in April 2024 as a tool to suppress Aedes aegypti. Only female mosquitoes bite; males do not bite or transmit disease.

The district said residents may notice more mosquitoes after each release, but that the added insects are harmless males. “While residents may visually see more mosquitoes in the area, Aedes aegypti biting pressure will gradually reduce over time,” said Tristan Hallum, the district’s director of scientific programs. “This program is species-specific and will not affect humans, pets, wildlife, or other insects, like bees or butterflies.”

The district said the releases are meant to supplement, not replace, traditional mosquito control, and urged residents to keep dumping standing water, maintaining pools, changing pet-dish water weekly, and using EPA-approved repellents.

Aedes aegypti, an invasive species that has spread across Los Angeles County since 2011, is difficult to control because it resists many insecticides and breeds in small containers around homes. Other California districts have tested similar methods. The Greater Los Angeles County Vector Control District reported a nearly 82% drop in Aedes aegypti in one release area in Sunland-Tujunga, and districts in the Inland Empire and Sacramento region have run comparable programs.

The district said Bassett is the only neighborhood scheduled for the program this year, and that it will use the launch to measure cost and effectiveness before deciding whether to expand elsewhere in the valley.

Residents can find program information at bit.ly/sgvmosquitomatch or by calling the district at (626) 814-9466.

The U.S. Forest Service has raised the fire danger level to “Very High” across the Angeles National Forest and the San Gabriel Mountains National Monument — the federal lands that rise directly above Altadena, Pasadena, and neighboring foothill communities — effective July 24 and continuing through Dec. 31, according to a Forest Service alert.

The Angeles National Forest Supervisor’s Office announced the change under Forest Order No. 05-01-26-12. Officials cited rising temperatures and drying vegetation that increase the probability of wildfire, the alert said.

“Very High” is one of six levels on the Forest Service’s fire danger scale, which runs Low, Moderate, High, Very High, Extreme and Critical. The forest had already been elevated to “High” on June 12 under a separate order.

The Forest Service said the escalation does not add new campfire restrictions beyond those already in effect at the “High” level. Open wood and charcoal fires remain permitted in developed campgrounds and picnic areas that have agency-provided fire rings or stoves. Propane and jellied-gas stoves and grills are permitted in non-developed areas with a valid California Campfire Permit. All stoves and campfires require a valid California Campfire Permit, available at https://permit.preventwildfiresca.org.

The signed order does formalize specific prohibited acts under federal law. Issued under 16 U.S.C. § 551 and 36 C.F.R. § 261.50(a), it prohibits building or using a wood or charcoal fire outside a developed recreation site; smoking outside an enclosed vehicle, building, developed recreation site or a cleared area three feet in diameter; and discharging a firearm, air rifle or gas gun outside authorized public shooting ranges.

Violations carry fines of up to $5,000 for an individual or $10,000 for an organization, imprisonment of up to six months, or both, under 16 U.S.C. § 551 and 18 U.S.C. §§ 3559, 3571 and 3581.

Exemptions apply to federal, state and local officers on duty and to organized rescue and firefighting personnel; to holders of Forest Service Permit No. FS-7700-48; and to licensed hunters during open season. Holders of a California Campfire Permit are not exempt from the listed prohibitions, according to the order.

Heat wave and air quality

The elevation came during an active Southern California heat wave. Forecasters at the National Weather Service were tracking a second, more intense heat episode on July 22 and 23, with widespread triple-digit temperatures forecast across the region and wildfire risk described as especially high in the mountains and foothills.

A weather service heat advisory covers the Santa Clarita Valley, San Fernando Valley, San Gabriel Valley, Santa Susana Mountains, the Interstate 5 corridor and the eastern and western San Gabriel Mountains, with forecast highs of 97 to 107 degrees. An extreme heat watch and warning cover the Antelope Valley, where highs of 100 to 108 degrees are forecast.

The South Coast Air Quality Management District issued an ozone advisory for parts of Los Angeles County effective 10 a.m. Thursday, July 23, through 8 p.m. Monday, warning of unhealthy air quality for sensitive groups in the San Fernando and San Gabriel valleys.

In June, the Los Angeles Times reported that coastal Southern California was expected to face a typical wildfire season from July through September, while cautioning that even typical conditions remain dangerous. Officials at a Southern California fire-preparedness meeting urged home-hardening measures.

Who is affected by the new order

The designation applies forest-wide and affects recreational visitors, cabin owners and forest concessioners across the Angeles National Forest and the San Gabriel Mountains National Monument, an area bordering Pasadena, Altadena, Sierra Madre, Arcadia, Glendora and Santa Clarita.

The Angeles National Forest Supervisor’s Office can be reached at (626) 574-1613.

The order remains in effect through Dec. 31.

Cone Camp participants prepare to launch a weighted line into a sugar pine tree in Pollock Pines on July 15, 2026. Photo by Anna Hoch-Kenney, CalMatters

A windowless warehouse on the outskirts of Davis shelters pieces of California’s forests.

Icy air swirls and fogs around 42,000 pounds of seeds — the past and the future of these trees, frozen in cardboard boxes. It smells like the woods on a snowy day.

“This is like the mothership of forestry in California right here,” said Stewart McMorrow, staff chief for wildfire resilience at Cal Fire, standing outside the heavy metal door of the state seed bank at Cal Fire’s Lewis A. Moran Reforestation Center in Davis.

Private landowners especially rely on these seeds — some now more than a half-century old — to reforest property destroyed by wildfire.

At the pace California is burning, it’s nowhere near enough.

Climate change and more than a century of overzealous fire suppression are now fueling wildfires so severe that they’re wiping out the very forests that need fire to thrive — leaving iconic landscapes at risk of turning into brush and scrub, permanently.

Over the past quarter century, high-severity wildfires have burned 2.3 million acres of California’s forestland so completely that the trees are unlikely to return on their own — according to a working draft of the state’s new reforestation strategy obtained by CalMatters.

California is counting on these forests to store carbon, protect water supplies, clean the air, and shelter wildlife. By 2071, one recent analysis reports, half of California’s forest area could be gone.

“Reforestation,” said Malcolm North, a scientist with the U.S. Forest Service Pacific Southwest Research Station, “is pretty damn important.”

Yet to replant even a quarter of the privately owned forestlands in the state, California would need to increase seed bank capacity by roughly 300%, according to Cal Fire — which means more seeds, more people, more space. And that wouldn’t solve the problem on federal land, which accounts for more than half the forests in the state and most of the lands that need replanting.

CalMatters reviewed a working draft of California’s reforestation strategy; the USDA California Climate Hub is developing it with state and federal agencies, the conservation non-profit American Forests, and the Governor’s Wildfire and Forest Resilience Task Force.

But both Sacramento and Washington have spent decades letting the money and staff needed to grow back California’s forests wither.

“We need to focus on reforestation as an emergency, as a state,” McMorrow said. “We are slowly losing our forestland, and we’re not catching up.”

Bleeding the federal workforce

Timber harvests once paid for much of the U.S. Forest Service’s efforts to replant trees.

But as new laws tightened endangered species and other public lands protections, logging in national forests declined. Severe wildfires also increased.

The combination devoured the Forest Service’s resources, and people: from 1998 to 2015, non-fire staff tasked with managing National Forest System lands decreased by 39%, according to a 2015 report.

With ever-increasing demands, a 2022 Forest Service document warned, there is a “critical need” to increase the number of staff “substantially dedicated” to reforestation.

Congress and the Biden Administration unstoppered additional money for a reforestation trust fund in 2021, a move championed by the conservation non-profit American Forests. Just a few years later, the Forest Service reported that it had replanted roughly 285,000 acres nationwide — the highest yearly total in more than a quarter century.

But the need still dwarfs action, and federally-directed work is lengthy and intense. Crews must clear dead and dying trees quickly to reduce the danger to people and the chance of reburns, a Forest Service spokesperson said. Finding seeds and growing seedlings can take a year or two, even before planting.

The federal government’s capacity to replant forests eroded away over time, and it will take time to rebuild it, said Solomon Dobrowski, a professor of landscape ecology at the University of Montana. Dobrowski’s research found that the reforestation gap spans millions of acres across the West and is likely to double or even triple in the coming decades.

“You don’t turn that ship around on a dime,” Dobrowski said.

Instead, the Trump administration cut the Forest Service significantly. The agency lost 20% of its staff last year.

“It just makes me cry at night … it’s basically a child swinging a wrecking ball,” said Hugh Safford, a forest and fire ecologist with the UC Davis Environmental Science and Policy Department and a former regional ecologist for the Forest Service. “Morale is down, capacity already was really minimal.”

And California keeps burning.

A widening gap

The loss of forests “is one of the least-known impacts of climate change and megafires,” said wildfire task force director Patrick Wright.

The draft strategy for California obtained by CalMatters comes with no dedicated funding. The goal, Wright said, is to put every agency and organization trying to replant California’s scorched forests on the same page.

The strategy calls for streamlining planning, prioritizing projects tackling critical human safety concerns and ecosystem issues like water supply, and increasing the supply of seeds, seedlings and workers.

It urges land managers to avoid adding more fuel to the fires, and recommends replanting at lower densities and with more natural spacing instead of the classic, closely-packed “pines in lines” grid. Scientists have linked high-density plantings to high-severity fires.

The most startling pieces, though, come from the draft strategy’s look at the current landscape. California would need to scale up reforestation by 35% annually to meet the state’s existing post-fire replanting goals, which start at 280,000 acres per year in 2030. The increase would take “significant funds,” the report said, because reforestation can cost up to $6,400 an acre.

But the current pace is lagging. Statewide, land managers have replanted roughly 254,000 acres of severely burned forest since 2020 — or around 16% of the area stripped of forest cover by high severity fires between 2020 and 2024 alone. The number is just 8% on federal lands, outside of wilderness areas.

Safford said the numbers are actually even more dire: Factoring in both wilderness areas and excluding forests likely to regrow on their own, his recent study reports that the U.S. Forest Service replanted just 1.2% of the agency’s California lands that wildfire denuded between 2016 and 2023.

It wasn’t always like this, said Safford. The Forest Service’s replanting efforts mostly kept pace with wildfires until around 2006.

“And then,” Safford said, “it just falls to shit.”

‘Nowhere near prepared’

For all the vitriol between Gov. Gavin Newsom and President Donald Trump over the care and raking of California’s forests, state and federal money — and people — often intersect on the landscape.

On California’s end, Cal Fire funds and conducts research, and provides grants for forest restoration on private, state and even federal land. Cal Fire also runs the reforestation center in Davis, where flats of glossy young conifers are gently misted with water in the summer heat.

McMorrow — tall and crisp in his navy Cal Fire uniform — can’t help but dig his hands into the dirt to pull out weeds tangling with the seedlings.

One of the most challenging chokepoints, McMorrow said, is finding the right seeds to grow these seedlings — getting climbers to the right spot, at the right time, to pluck ripe cones from the treetops.

“Believe me, I do it,” said McMorrow, who created a tree-climbing program at Cal Fire. “We are trying to meet the demand that’s in front of us, and it’s crushing.”

Yet the money for Cal Fire’s efforts — cobbled together from the state budget, federal grants and other one-time funds — represents a relatively small and ever-changing fraction of Cal Fire’s multibillion-dollar budget.

The nursery in Davis shut down in the early 2000s, a casualty of across-the-board state budget cuts. Though the seed bank freezer stayed on, the reforestation center didn’t fully reopen until after the Legislature in 2017 tapped a 2012 fee on wood products to bring it back online.

Scaling up and upgrading the facility now carries an estimated $26.2 million price tag; this year’s state budget included about $1.2 million to fund preliminary planning.

Meanwhile, other funding is on the line. California’s climate regulators — chaired by Newsom appointee Lauren Sanchez — voted in May to overhaul a key climate program  in ways that could substantially reduce, or even eliminate, up to $200 million a year for wildfire resilience. Grants for reforestation are among the many competing priorities for this funding.

While the Proposition 4 climate bond includes $1.5 billion for wildfire and forest resilience, state leaders are spending down the bond quickly.

“The truth of the matter is that California is probably, infrastructurally speaking, in a better place than any other western state,” Safford said.

“What that tells you is how piss-poor the capacity is in general in the Western U.S., because California is nowhere near prepared for the scale of this.”

Cone hunting

On the banks of Jenkinson Lake in the Sierra Nevada foothills, Stella Krone and Elyse Wohlenberg wrestled with a slingshot that towered over the two of them. It took their combined strength to slot the bungee into position, then Wohlenberg stepped back.

“All clear?” Krone asked, kneeling in a clearing and pointing the slingshot at a Douglas fir 50 yards away. “Firing!”

Krone, Wohlenberg, and dozens of other hard-hatted people were there, crunching over conifer needles, for Cone Camp — a training program led by American Forests with support from Cal Fire and the Forest Service.

The campers — some forestry professionals, some interested laypeople — peeled off with oversized slingshots and souped-up potato guns to learn how to knock cones loose from tree branches. That’s how they check the cones for ripeness and viability, before sending someone up the tree to collect them for a seed bank.

The problem was, there were hardly any. Last year’s dry cones rattled to the forest floor as Krone and another camper jiggled the rope they’d shot into the canopy.

“So far, not a great cone year,” said Leana Weissberg, American Forests’ California director.

In the clearing, the instructor asked whether the group was ready to try again.

“Let’s go,” Krone said. “We’re cone hunters for a reason.”

CalMatters.org is a nonprofit, nonpartisan media venture explaining California policies and politics.

[photo credit; City of Pasadena]

The center, at 1020 N. Fair Oaks Ave. in northwest Pasadena, gives residents an air-conditioned place to escape the heat. Forecasters have warned that the heat poses a high risk of illness for older adults, young children and people without air conditioning.

The city said the cooling center will be open from 8 a.m. to 8 p.m. on Thursday and Friday, July 23 to 24, and from 11 a.m. to 7 p.m. Saturday and Sunday, July 25 and 26.

The National Weather Service issued a heat advisory for much of Los Angeles County beginning Wednesday morning, with highs of 88 to 96 degrees common in inland-coast areas, including Downtown Los Angeles, and overnight temperatures expected to bring less relief than usual.

Local public health officials have urged residents to stay hydrated and cool, limit time in the sun and check on older neighbors and others at higher risk of heat illness, which can range from heat cramps to heat stroke.

The Jackie Robinson Community Center is the city’s designated cooling center, a site Pasadena identifies in its extreme-weather planning and opens specifically as a cooling center during heat events. The city lists the center on its Extreme Weather Portal and classifies its other community and recreation centers and its public libraries as air-conditioned indoor relief rather than official cooling centers.

Under state public health guidance, cooling centers are air-conditioned facilities meant to provide relief from heat, particularly for higher-risk residents such as older adults, young children and people with chronic health conditions. The designation signals that residents without air conditioning at home and others seeking relief may use the center during posted hours, whether or not they take part in its programs.

State guidance also recommends that official cooling centers meet Americans with Disabilities Act accessibility standards, including accessible entrances, restrooms and interior routes.

For accessibility information and requests, contact the city at CSC@cityofpasadena.net or (626) 744 7311.

The advisory is scheduled to remain in effect until 8 p.m. Monday.

Pasadena and Altadena residents are being urged to take precautions against dangerous heat as a Heat Advisory remains in effect across the region through Monday, July 27

The Los Angeles County Department of Public Health said unusually warm overnight conditions are expected to accompany the daytime heat, offering less relief than usual, through Monday.

Taking precautions is the most important way to prevent heat-related illness such as heat exhaustion, heat stroke and heat cramps, as well as heat-related death, the department said.

“Heat causes more deaths in the U.S. annually than floods, storms, and lightning combined. Those most likely to get ill during the heat include older adults, young children, outdoor workers, athletes, and individuals with chronic medical conditions,” said Muntu Davis, MD, MPH, the Los Angeles County Health Officer, in the release.

“Remember, your safety and the safety of others is crucial during extreme heat conditions. If you or someone around you experiences symptoms of heat stroke or heat exhaustion, such as dizziness, nausea, rapid heartbeat, confusion, or passing out, seek medical help immediately.”

The department advised residents to drink water throughout the day even when not thirsty, to limit time outdoors during the hottest hours, and to wear lightweight, light-colored clothing. It also recommended wearing a hat or using an umbrella and applying sunscreen of SPF 15 or higher.

Residents were reminded never to leave children or pets in a parked vehicle, even briefly and even with windows cracked, and to call 911 if they see a child or pet left alone in a car.

Public Health identified several groups at higher risk, including people who are sick or have chronic conditions, older adults, pregnant women, young children, people who live alone, pets, outdoor workers and athletes, and anyone without air conditioning. The department urged residents to check on vulnerable neighbors during the advisory.

The department said 911 should be called immediately for anyone showing signs of serious heat illness, including a body temperature of 103 degrees or higher, confusion, fainting, a fast and strong pulse, headache, dizziness, nausea, or hot, red skin that may be dry or damp.

For residents without air conditioning, the department recommended cool showers or baths, using the stove and oven less, and spending time in air-conditioned spaces such as libraries, cooling centers or shopping malls. Free cooling centers, splash pads and community pools are available across the county; locations can be found at ready.lacounty.gov/heat or by calling 211, a toll-free line available around the clock. 

A prolonged heat wave will keep Pasadena under triple-digit temperatures through the weekend, forecasters said Thursday, with little relief overnight.

The National Weather Service in Los Angeles/Oxnard reported highs near 99 degrees Thursday, climbing to about 100 degrees Friday and Saturday. Overnight lows will remain in the upper 60s to around 70 degrees, limiting recovery from daytime heat.

Thursday’s conditions include sunny skies and calm winds shifting to a southwest breeze near 5 mph in the afternoon. Similar patterns are expected Friday and Saturday, with light winds and mostly clear skies.

Forecasters said temperatures will ease slightly Sunday and Monday, with highs near 96 degrees, before dropping closer to 93 degrees Tuesday and Wednesday. Despite the modest cooling, readings will remain above seasonal averages.

No rain is forecast for Pasadena during this period. Winds will stay light, generally calm in the mornings and shifting to gentle south or southwest breezes in the afternoons.

The National Weather Service has issued heat advisories through Monday evening, warning of elevated risks for heat illness. Officials urged residents to avoid strenuous activity during peak afternoon hours, stay hydrated, and check on vulnerable neighbors.

Pasadena’s urban environment may intensify the heat, particularly in areas with limited shade. The combination of high daytime temperatures, warm nights, and humidity increases the risk of heat stress, especially for those without air conditioning.

By midweek, temperatures are expected to remain above normal but less extreme. Another round of heat could develop late next week, forecasters said.

Here is the Pasadena forecast from the National Weather Service as of 3:11 a.m. Thursday:

Today: Sunny and hot, with a high near 99. Calm wind becoming southwest around 5 mph in the afternoon.

Tonight: Mostly clear, with a low around 70. South southwest wind around 5 mph becoming calm in the evening.

Friday: Increasing clouds and hot, with a high near 100. Calm wind becoming south around 5 mph in the afternoon.

Friday Night: Cloudy during the early evening, then gradual clearing, with a low around 67. South southwest wind around 5 mph becoming calm in the evening.

Saturday: Sunny and hot, with a high near 100. Calm wind becoming south southwest around 5 mph in the afternoon.

Saturday Night: Mostly clear, with a low around 67.

Sunday: Sunny and hot, with a high near 96.

Sunday Night: Mostly clear, with a low around 66.

Monday: Mostly sunny and hot, with a high near 96.

Monday Night: Mostly clear, with a low around 65.

Tuesday: Sunny, with a high near 93.

Tuesday Night: Mostly clear, with a low around 65.

Wednesday: Sunny, with a high near 93.

A prolonged heat wave will grip Pasadena through early next week, with temperatures climbing into the upper 90s and near 100 degrees, forecasters said Wednesday. The National Weather Service warned that elevated humidity and warm overnight lows will increase the risk of heat-related illness. A heat advisory remains in effect through Monday evening.

Sunny skies will dominate Wednesday, with highs near 96 degrees and light southwest winds around 5 mph in the afternoon. Overnight lows will stay near 65 degrees, offering little relief.

Thursday and Friday are expected to be the hottest days, with highs reaching 98 to 99 degrees. Nights will remain warm, with lows in the upper 60s. Forecasters said the lack of cooling at night could make conditions especially dangerous for residents without air conditioning.

Temperatures will ease slightly over the weekend, with Saturday forecast at 93 degrees and Sunday at 95 degrees. Clear skies will continue, with lows in the mid-60s. Monday will remain hot, with highs near 94 degrees, before a modest cooling trend begins Tuesday, when highs dip closer to 92 degrees.

No rainfall is expected during the period. Winds will stay light in Pasadena.

The National Weather Service urged residents to stay hydrated, avoid strenuous outdoor activity during peak afternoon hours, and check on vulnerable neighbors. Cooling centers are expected to see increased use as the heat persists.

Forecasters said the heat advisory will likely expire Tuesday as stronger onshore flow brings slight cooling. However, long-range models suggest another heat event could develop later next week.

Here is the Pasadena forecast from the National Weather Service as of 3:05 a.m. Wednesday:

Today: Mostly sunny and hot, with a high near 96. Calm wind becoming southwest around 5 mph in the afternoon.

Tonight: Mostly clear, with a low around 65. Southwest wind around 5 mph becoming calm in the evening.

Thursday: Sunny and hot, with a high near 98. Calm wind becoming southwest around 5 mph in the afternoon.

Thursday Night: Mostly clear, with a low around 67. Southwest wind around 5 mph becoming calm in the evening.

Friday: Sunny and hot, with a high near 99. Calm wind becoming south around 5 mph in the afternoon.

Friday Night: Cloudy, with a low around 66.

Saturday: Mostly sunny, with a high near 93.

Saturday Night: Mostly clear, with a low around 67.

Sunday: Sunny, with a high near 95.

Sunday Night: Mostly clear, with a low around 66.

Monday: Sunny, with a high near 94.

Monday Night: Mostly clear, with a low around 65.

Tuesday: Sunny, with a high near 92.

[Artist Rendering]

The National Weather Service said the combination of above-normal temperatures, low humidity, dry vegetation and breezy conditions will increase the risk of rapidly spreading wildfires.

“With hotter and more unstable conditions, there will be an increased risk for large plume dominated fires across the interior, especially in the Thursday through Monday time frame when the heat wave peaks and humidities lower,” the weather service said.

Warm overnight temperatures and poor overnight humidity recovery are expected to further elevate the fire danger, particularly in foothill and mountain communities, the NWS said.

Forecasters said very dry air could spread into portions of the interior Sunday and Monday, dropping humidity levels to between 5% and 10%.

The weather service also forecast widespread moderate to high heat risk across the region from Wednesday through Monday, with triple-digit temperatures expected in many valleys, mountain communities and desert locations.