Saturday, November 15, 2025

Flood Watch in Effect as Heavy Rain Threatens Pasadena and Altadena Saturday

[Updated   5:55 a.m.] Pasadena and Altadena are under an areal flood watch until 10 p.m. Saturday, with the National Weather Service warning of heavy rainfall, saturated soils, and the potential for flooding in low-lying and urban areas.

“Concerned about what today will entail, so [we] encourage residents to remain vigilant, especially if in the burn scar or flood-prone areas,” Pasadena Chief Communications Officer Lisa Derderian said early Saturday. “Please allow extra time driving and greater distance between vehicles because traffic accidents always rise during rain and excess water on roads.”

Forecasters predict 1 to 2.5 inches of rain, with locally higher amounts possible. Rainfall rates could reach 0.5 to 1 inch per hour, raising the risk of excessive runoff and flooding in rivers, creeks, streams, streets, highways, underpasses, and areas with poor drainage. The flood watch was issued early Saturday morning by the National Weather Service, which noted that “excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.”

The ground in the San Gabriel Valley is already saturated from recent storms, increasing the likelihood of flooding even with moderate rainfall. Residents are urged to monitor weather alerts and avoid driving through flooded roadways, forecasters said.

Saturday’s forecast calls for a 100% chance of rain throughout the day, with a high near 62 degrees and an overnight low around 51. Winds will be light to moderate, with gusts up to 9 mph from the southeast during the day, easing to 4 mph by nightfall. Humidity will remain high, ranging from 81% to 96%, and visibility may be reduced during periods of heavy rain. UV Index is forecast at 1 (Low).

Rain is expected to taper off overnight, though a 77% chance of light showers remains into the evening. Sunday will bring slightly drier conditions, with a high near 71 degrees and continued chances of light rain.

This forecast is based on data from the National Weather Service as of 5:24 a.m. Saturday.