LOS ANGELES, CA — Flash flood warnings were in effect Sunday morning across parts of Southern California as heavy rain from Post-Tropical Cyclone Rachel moved through the region and raised the risk of dangerous flooding. The National Weather Service warned that portions of Orange, Riverside and Imperial counties could see life-threatening runoff, especially in low-lying and flood-prone areas.
Officials told people in the warning areas to move to higher ground and stay out of floodwaters. The alerts came after days of damaging surf and coastal flooding along the coast, where storm impacts had already disrupted neighborhoods, streets and public access points.
Orange County warning covered San Clemente, Dana Point and San Juan Capistrano
The first flash flood warning was issued around 4 a.m. for parts of southern Orange County, including San Clemente, Dana Point and San Juan Capistrano. That warning remained in place until 7 a.m., according to the National Weather Service.
Forecasters said the danger included rapid flooding on roads and in drainage channels, along with the possibility of water covering streets with little notice. Residents were urged not to walk or drive through flooded areas, where even shallow water can create serious hazards.
The warning area showed how far inland the storm’s rain bands had reached after affecting the coast for several days. While the rain was the immediate threat Sunday morning, the broader storm had already caused erosion, street flooding and public safety measures in coastal communities.
Blythe and other desert communities faced flooding risk into late morning
A separate flash flood warning covered northeastern portions of Riverside and Imperial counties, including Blythe, Palo Verde and Ripley, until 10:30 a.m. Sunday. The National Weather Service said rain had already been falling hard in that area early in the morning.
By 8:09 a.m., between 0.75 and 1.75 inches of rain had already accumulated in the eastern warning area, with as much as another half-inch still possible. Forecasters said that amount could quickly overwhelm roads, washes and other drainage routes.
The warning also included parts of Interstate 10 and state Routes 78 and 95. Officials warned that flooding could affect highways, underpasses, creeks and other low-lying spots, making travel dangerous or impossible in some locations.
Forecasters warned of life-threatening runoff on roads, highways and underpasses
The National Weather Service described the flooding threat as potentially life-threatening, especially where water could move quickly across pavement or collect in dips and channels. That included not only major roads, but also smaller crossings and flood-prone neighborhoods near creeks and washes.
In Southern California, flash flooding can develop with little warning when rain bands stall or intensify over the same area. The risk is especially high in places where dry terrain, steep slopes and concrete drainage systems can send water racing downhill or across roadways.
Residents in the warning zones were told to avoid driving through floodwaters and to be ready to change routes if roads began to close or flood. Emergency officials also urged people to pay close attention to local alerts as conditions changed through the morning.
Coastal flooding and damaged infrastructure continued along the Orange County and Los Angeles County shoreline
The flooding threat on Sunday followed several days of surf damage and unusually high tides along the coast. Long Beach, Newport Beach and Malibu were among the communities hit by high waves and water intrusion that damaged infrastructure and prompted emergency actions.
In Long Beach, mandatory evacuations were ordered for homes along portions of Seaside Walk after several structures were found unsafe to occupy. Newport Beach declared a local emergency and closed Newport Pier, Balboa Pier and the Wedge while crews worked to reinforce protective sand berms.
Along the Los Angeles County coastline, a coastal flood warning remained in effect until 3 p.m. Sunday. Forecasters said high tides near 8 feet and surf of 5 to 8 feet could lead to major flooding and beach erosion.
Rain totals expected to ease by Tuesday as warmer, drier weather returns later in the week
The National Weather Service said most communities in the region could receive between a quarter-inch and an inch of rain through Monday. Higher totals were possible in the San Gabriel Mountains, where terrain can intensify runoff and increase the risk of localized flooding.
Rain was expected to taper off by early Tuesday, giving Southern California a break after a stretch of storm-related hazards. Forecasters said warmer and drier conditions should return later in the week.
Even with improving weather ahead, officials continued to warn residents to stay away from flooded roads and hazardous coastal areas until conditions fully stabilized. The storm’s impacts were still unfolding Sunday as rain, runoff and coastal flooding overlapped across multiple counties.