Flood Watch Issued as Storm Brings Heavy Rain, Debris-Flow Risk to Southern California

A storm system moving along the California coast prompted the National Weather Service (NWS) office serving Los Angeles and Oxnard to issue a Flood Watch for Wednesday, October 21, through Thursday, October 22, 2026. The watch was issued Tuesday, October 20 at 12:11 p.m. PDT. For the Malibu coast and Santa Monica Mountains, it runs from Wednesday afternoon through Thursday afternoon; for Santa Barbara County areas, it runs from Wednesday morning through Thursday afternoon, according to the NWS watch bulletin.

According to the NWS, the storm is expected to peak from late Wednesday morning through late Thursday morning. Rainfall totals across most coastal and valley areas are forecast at 0.5 to 1.5 inches, while south-facing mountains and foothills could see 1.5 to 3 inches. The NWS watch bulletin states rain rates of 0.5 to 1 inch per hour are possible. The Watchers, citing a Weather Prediction Center outlook, reported that localized rates could reach up to 2 inches per hour where thunderstorms repeatedly develop over terrain.

Where the Flood Watch Applies

The Flood Watch covers areas stretching from Santa Barbara County — including Santa Ynez and Gaviota, and coastal communities such as Montecito and Goleta — down through the Malibu coast and the Santa Monica Mountains, according to the NWS watch bulletin. Los Angeles County is expected to average around 1.5 inches of rain, with 2 to 3 inches possible in terrain-enhanced zones and under slow-moving thunderstorms, MyNewsLA reported.

Targeted flood watches were also issued for Malibu, Malibu Bowl, Pacific Palisades and Topanga, effective Wednesday afternoon through Thursday afternoon, according to MyNewsLA and the NWS watch bulletin.

Burn-Scar Debris Flow Concern

The NWS said minor flooding and debris flows are possible, especially near recent wildfire burn scars, where scorched hillsides shed rainfall more quickly and can mobilize rock, mud and ash into roads and structures. The Watchers reported that "urban areas, burn scars, slot and box canyons, dry washes and arroyos are particularly vulnerable to rapid runoff."

The Weather Prediction Center placed portions of Southern California, the Southwest and the Four Corners region under a Slight Risk of excessive rainfall for October 21 and 22, The Watchers reported.

Additional Hazards

Beyond inland flooding, the NWS flagged dangerous rip currents and elevated surf along the coast, with a moderate risk of minor tidal overflow or coastal flooding. The Watchers also reported a Storm Prediction Center Slight Risk of severe thunderstorms for central and eastern Arizona on October 21, with conditions favoring supercells capable of damaging winds, large hail and one or two tornadoes further east, though this risk is centered outside Southern California.

MyNewsLA reported that forecasters also flagged a small chance — 5% or less — of a weak tornado as the storm's upper-level low moves inland late Wednesday night into Thursday morning. The NWS also warned of gusty winds and small hail potential amid isolated to scattered thunderstorms.

What Comes Next

The NWS said conditions are expected to improve starting Friday as dry weather returns to the region. MyNewsLA reported that daytime highs during the storm were forecast in the mid-60s to lower 70s Fahrenheit across Los Angeles County.

• Flood Watch: Wednesday afternoon–Thursday afternoon for the Malibu coast/Santa Monica Mountains; Wednesday morning–Thursday afternoon for Santa Barbara County (NWS)
• Peak rain: late Wednesday morning through late Thursday morning (NWS)
• Rainfall: 0.5–1.5 inches coastal/valley; 1.5–3 inches on south-facing mountains/foothills (NWS)
• Rain rates: 0.5–1 inch/hour per NWS; locally up to 2 inches/hour under thunderstorms per The Watchers/Weather Prediction Center
• Key risk: debris flows and flooding near recent burn scars (NWS)