Local cities are building berms on beaches and putting out sandbags near vulnerable neighborhoods as the region braces for up to an inch of rain.
Some light rain was already falling Tuesday afternoon in parts of Orange County and in mountain communities from Temecula to Idyllwild. The heavier rain is expected to hit by Wednesday morning.
Full Southern California weather forecast here.
A flash flood watch was in effect starting Tuesday afternoon and lasting until 1 a.m. Thursday in Inland Empire communities from Temecula to Lake Elsinore, Hemet, Riverside and Yucaipa.
A winter storm warning was in effect until Thursday 7 p.m. in mountain communities to the east of that, around Yucaipa, Big Bear Lake and Crestline.
ORANGE COUNTY
Communities in Trabuco Canyon in the Holy Fire burn area have been issued voluntary evacuation warnings. Officials say the warnings are out of an abundance of caution.
Significant rainfall is expected to hit the area by around 3 a.m. Wednesday and flooding and debris flows are possible.
The voluntary evacuation is for homes in the Trabuco Creek, Rose Canyon and Mystic Oaks / El Cariso areas.
Orange County residents were urged to sign up for OC Alert to get the latest notifications.
Orange County crews prepare for possible flooding
Orange County bracing for rain, possible flooding
In Seal Beach, bulldozers were building a sand berm in front of beachfront homes. The 14-foot berm goes up every year, as the community learned its lesson in 2014 when swells from Hurricane Marie flooded homes along the boardwalk.
"If you go back historically we've had a lot of standing water back at the homes," said Chris Pierce, with the Seal Beach Marine Safety Department. "That's usually the result of high surf, rain event and high tides combined. When those three things come together we have seen a lot of standing water that has come back to the homes. In recent years though, we've been pretty on it to make sure that doesn't happen."
SAN GABRIEL VALLEY
Duarte and other communities along the 210 corridor were hit hard by fire and flooding a few years ago.
But this fire season they escaped most of the wildfires and the vegetation above vulnerable neighborhoods has grown back.
San Gabriel Valley communities preparing for storm
While K-rails remain in place to contain potential flooding, many residents say they don't expect serious problems.
Some even welcome the rain.
"We need rain," said Duarte resident Taress Clark. "We live in California. I know in past years we've had a shortage of rain and the drought. We need the rain. Bring it on!"
INLAND EMPIRE
Residents in San Bernardino whose homes are along blackened hillsides are bracing for rain and possible debris flows.
Rain totals are not expected to cause wide spread flooding, but the potential is there. The San Bernardino County Fire Department will be monitoring hillsides for movement and have equipment and firefighters on standby.
"After the fires will always come the rains and that's a big issue because...it's harder to defend against the rain because you don't see it coming," said Jessie Carrillo of San Bernardino.
Carrillo was out surveying the area close to his sister's home Tuesday afternoon. He said even without a burn scar to worry about some areas are prone to flooding.
San Bernardino residents along blackened hillsides bracing for possible debris flows
"Anytime there is elimination of undergrowth you are going to get more water. We are just going to pray it isn't that bad," Carrillo said.
Other residents were not worried.
Mike Hatoum of San Bernardino said he hopes the rain will rid his street and home of the heavy smoke smell left in the wake of the fires.
"It will clean up a little bit and it will bring the ashes and everything down," Hatoum said.