After record-setting highs, cooler-than-normal temperatures forecast for Southland

After last week’s record-setting high temperatures, Southern California will experience cooler-than-normal temperatures and occasional drizzle through midweek, forecasters said Monday.

The cool weather is being caused by a low-pressure trough that could also spark thunderstorms and lightning through Wednesday, the National Weather Service said. A high-pressure system is expected to begin developing Thursday and lead to warmer temperatures and possible Santa Ana winds by the weekend.

“We’re under a low pressure right now. Then we’ll transition into a nice weekend,” said Bonnie Bartling, a weather specialist with the National Weather Service in Oxnard.

Light drizzle was reported across the Los Angeles region Monday and kept the California Highway Patrol busy responding to dozens of fender-benders and minor spinouts on roads and freeways, authorities said.

A downpour Monday afternoon in the Angeles National Forest caused a mudslide near the Chantry Flats Campground above Monrovia. The Los Angeles County Fire Department dispatched a search-and-rescue team to look for hikers who might have been trapped by the mud but reported finding no victims.

By Monday afternoon, most areas had reported just a trace of rainfall. Pasadena, with one of the higher reports, had received 0.20 inches of rain, according to the weather service. Daily rainfall through Wednesday is expected to be less than an inch across most of Southern California.

robert.lopez@latimes.com