Rains are soaking Los Angeles for the first time in months. Is it enough to reduce wildfire risks?

For the first time in months, widespread rainfall is drenching the Los Angeles area as a strong band of moisture from a dissipated tropical storm moves north.

By Thursday morning, much of Southern California had already recorded some measurable — though mostly minor — rainfall, while a few inland areas were experiencing localized flooding that officials warned could get worse and expand. Much of the region remains under a flood watch through early Friday.

“As the day wears on … we could definitely start getting those heavier showers and thunderstorms developing,” said Rich Thompson, a meteorologist with the National Weather Service in Oxnard. “Some areas will have a lot of rain.”

Some of the heaviest rain fell in San Bernardino County, triggering multiple mudslides that trapped drivers on Route 38 in Big Bear and knocked down power lines in Oak Glen.

Wet storms across Southern California in September are unusual, but not unheard of, Thompson said. Monsoonal storms from the east — usually confined to the mountains and deserts — are more typical this time of year, he said, but every once in a while a tropical storm from the eastern Pacific pushes north, bringing bands of rain.

On Wednesday, remnants of former Tropical Storm Mario started to move into Southern California, boosting humidity and the chance for showers and thunderstorms.

The most significant rainfall and strongest storms were forecast for Thursday. Most populated areas of Los Angeles, Orange, San Diego and Ventura counties can expect to get up to a quarter- to a half-inch of rain, while some mountain and desert areas could see up to an inch, according to the National Weather Service.

But some areas could get as much as 2 inches of rain locally, depending on the strength and location of the developing storms. Under certain circumstances, officials are warning of storms that could bring dangerous lightning, gusty and erratic winds and heavy rains that could cause localized flooding.

“Rainfall rates capable of causing flash flooding, mud, and debris flows have already occurred earlier this morning, and daytime heating will only serve to destabilize the environment later today,” the National Weather Service posted in its Thursday forecast discussion.

The Santa Monica Mountains and much of the inland Southern California remain under a flood watch through early Friday, with rain rates reaching up to a half-inch per hour in some areas — or possibly higher. The National Weather Service warned that “excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.”

In San Bernardino County, officials issued a more elevated flood advisory Thursday morning, saying that Twentynine Palms and the Yucca and Morongo valleys “will experience flooding,” having already received half an inch of rain, and more on the way.

California

Southern California weather takes Florida turn as tropical storm remnants threaten heavy rain, flooding

For the rest of the week, Southern California will feel more like “Florida West,” forecasters said, as remnants of Tropical Storm Mario move north, boosting humidity and the chance for strong thunderstorms.

Sept. 17, 2025

Officials there were responding to “minor flooding and accidents due to wet roads on State Route 62,” the advisory said. Some local residents reported flooded roads in and around Twentynine Palms.

The rain triggered major flooding Thursday afternoon along State Route 38 in Big Bear, temporarily trapping dozens of motorists and closing the road in both directions, according to Caltrans.

Crews cleared mud, debris and trees from the road and freed the majority of motorists around 7 p.m. However, a small group of drivers was still stuck at 10 p.m. with Caltrans predicting it would take another hour or two to reach them.

Heavy debris flows were also reported in the town of Oak Glen, where a wave of mud was captured on video rushing down a hillside, knocking over power lines and slamming into vehicles, according to reporting from ABC7.

“It kind of sounded like an earthquake was coming,” local resident Denise Romo told the station. “When I opened my kitchen window I just see the first wave of mud, and it already had trees, mailboxes, a bunch of debris.”

Search and rescue crews were dispatched to the communities of Forest Falls and Oak Glen to assist residents trapped by the slides.

Flooding concerns would extend further north into Friday, with parts of the Central Valley, Sierra Nevada and its surrounding foothills also under a flood watch.

While some mountain and desert areas have seen recent precipitation from monsoonal storms, downtown Los Angeles hasn’t had any measurable rainfall since early May, according to the National Weather Service.

But despite the widespread rains Thursday, officials said it likely wouldn’t be enough to pull southwestern California out of “severe drought” conditions, which the region has remained in since March, according to the the U.S. Drought Monitor. It’s also likely not enough to eliminate the threat of another punishing wildfire season — often most dangerous during the upcoming Santa Ana winds season.

“It’s nice to have this rain, every little bit helps,” Thompson said. “But in terms of impacts on fire season … this would have a very marginal effect.”

Fire officials typically don’t consider the threat for fires diminished until at least 2 to 4 inches of rain has fallen, and only a few isolated areas might get 2 inches from this tropical moisture.

But, Thompson said there could still be some benefit.

“It might slow things down a little bit the next week or two,” he said.

Early Thursday morning, downtown Los Angeles, UCLA, Anaheim, Oceanside and Palm Springs had already recorded around a tenth of an inch of rain, according to the National Weather Service.

A few places had seen a bit more: Carlsbad and Chula Vista received almost a quarter-inch; San Diego International Airport and Coronado saw almost a half-inch; Riverside had seen three-tenths of an inch.

These totals will likely increase as the day goes on.

But even when rain isn’t falling, Southern California will feel the effects of the moist air mass over the region. Forecasters noted that atmospheric moisture readings from San Diego almost mirrored those from Key West on Thursday — or about 200% of normal for Southern California.

“It will be muggy out there,” the weather service warned. “Off and on again showers to continue as well, with isolated thunderstorms. Expect slick roads.”

While Los Angeles should dry out by Saturday, forecasts show that there’s the potential for another round of tropical weather next week, but it’s too early to tell what will materialize.

Long-range forecasts published this week predict that Southern California could remain in an above-average rainfall pattern for the next week, but it likely won’t last. Precipitation outlooks for the month of October — which marks the officials start of California’s rainy season — did not show an uptick in rainfall.

And forecasters are expecting a La Niña cycle to emerge soon and remain in place through December, a shift in climate patterns that historically swings the state toward drought, especially in Southern California.

Times staff writers Alex Wigglesworth and Clara Harter contributed to this report.