First California Storm Of Season (RECAP)

California experienced its first widespread soaking of the season primarily on October 13 and 14. This storm also brought the first round of heavy Sierra snowfall so far this fall.

Preliminary Impacts

A coastal low dove southward along the West Coast on Oct. 13, first bringing impacts to Northern California. There were about 50 reports of flooding in the state that day, particularly in the Bay Area.

Among those were a few reports of minor rockslides, but in the East Bay near Fairview, California, a "large amount of mud" was reported along a stretch of Palomares Road, according to the National Weather Service.

Rain, Storms and Sierra Snowfall

By Oct. 14, this storm shifted south, bringing rain from the Central Valley into parts of Southern California, with the first significant snow falling in the Sierra Nevada Mountain Range.

The first severe thunderstorm watch was issued for the L.A. Basin in over 17 years, the first since Jan. 27, 2008.

There were over a dozen reports of flash flooding Oct. 14 in the Southland, including flooding on I-10 at the 110 connector in Downtown L.A., flooding on I-5 near Sheldon St., at the I-210 connector in the San Fernando Valley and the 101 freeway at Seaward Ave. in Ventura County. Two northbound lanes of Route 99 were flooded at California Avenue in Bakersfield, as well.

Rainfall of 1-4 inches was widespread across California, with isolated totals approaching 6 inches across higher elevations.

The heaviest rain prompted some flash flood warnings, including for the Palisades burn scar in L.A County.

Wind gusted as high as 66 mph atop La Granada Mountain in Ventura County. Multiple trees were downed along the 101 freeway near Balboa in western L.A. County.

Rainy Season Ahead

California has distinct wet and dry seasons.

That's because the jet stream that typically delivers strong Pacific storms to the West Coast and California weakens and shifts well north in summer.

Fall is the transition period in California. Sometimes, strong Santa Ana winds fan large wildfires in October.

But occasionally, Pacific storm systems can sag far enough south to spread rain into at least Northern California, if not as far south as L.A. and San Diego.

About 82% of the average precipitation in Los Angeles falls from December through March. This often happens as strong Pacific storms tap deep plumes of moisture known as atmospheric rivers.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.