A 9-mile stretch of Pacific Coast Highway (State Route 1) was closed in both directions.
North- and southbound lanes of PCH have been closed between Yerba Buena Rd. and Las Posas Rd. due to mudslides and fallen rocks.
The closure began Saturday night and was expected to remain in place while heavy rain continues in the area. Caltrans geologists will assess the road and surrounding conditions as weather permits.
US 101, State Route 23 (Decker Rd.), or Kanan Rd. are alternate routes.
Three separate rock slides had PCH closed up to Point Mugu. All lanes were closed from Kanan-Dume Road in Malibu to Las Posas Road near Point Mugu. At about 7 a.m. Monday, a portion of Kanan-Dume Road was reopened.
The debris flow began just after 9 p.m. Sunday following hours of steady rainfall. About 3 feet of mud and boulders was cleared away, but officials await a geologist to give the "all clear."
Drivers who need to get to Ventura County are being rerouted to the 101 Freeway.
Highway 18 is closed from Green Valley Lake to Big Bear Dam because of rock slides, according to Caltrans.
State Route 2 is closed from Wrightwood to La Canada due to rock slides. Three feet of snow is expected in the same area. Caltrans did not expect to send crews due to the dangerous weather.
The rain forced closures of all county roads within the Station Fire burn area at 2 a.m. Sunday including Angeles Forest Highway, Big Tujunga Canyon Road and Upper Big Tujunga Canyon Road. Residents living in the burn areas are not permitted to use the roads until the closures are lifted. Residents were advised to remove their vehicles from streets.
The storm is expected to last until Wednesday, with consistent rainfall in the foothills, and then there is a possibility of another storm over the holiday weekend.
Rain brought down a heavy tree on top of an SUV and blocked traffic in Woodland Hills Monday.
Downtown L.A.'s rainfall of 2.3 inches on Sunday broke a record held since 1921. Long Beach's 1.53 inches nearly tripled the previous mark of .52. In San Gabriel, the 3.2 inches of rainfall shattered the record of 1.9 inches.
The rain has played a part in a lot of accidents and road closures across L.A. County. The California Highway Patrol reported 1,216 accidents on Saturday and Sunday in L.A. County.
The 710 Freeway in and out of Long Beach was closed for about six hours on Sunday night due to flooding. Lanes were closed at Willow Street at 10:10 p.m.
The water was several feet deep, and some people who tried to drive through the water got stuck.
"Several people pushed their car out themselves. Other people were towed out," said CHP Officer Tippett.
Authorities said several cars collided on the 710 Freeway because of the flooding, but there were no major injuries.
In Pomona, the southbound 71 Freeway remains closed due to flooding, and Mission Boulevard is also closed in both directions. The closure has been in effect since Sunday morning.