The three-day heat wave oppressing many of the inland valleys and foothills of Southern California is expected to let up on Sunday, but not before a brush fire caused some tense moments in the Temecula area Saturday,

Since Thursday, a ridge of high pressure has warmed Southern California, prompting weather officials to warn of an enhanced heat risk on Saturday. Temperatures are expected to rise well into the 90s in the San Fernando and San Gabriel valleys and as high as 106 in the Antelope Valley, the National Weather Service said.

People in those areas were urged to avoid working outdoors during the hottest part of the afternoon and to stay hydrated.

See the most-read stories this hour >>


The Southland heat wave has not produced any records, but weather service meteorologist Joe Sirard called the temperatures “significantly above normal,” from 10 to 20 degrees higher than average in some parts of the Southland.

The hot conditions have fire crews on alert. Los Angeles firefighters knocked down a two-acre brush fire in West Hills in the San Fernando Valley on Saturday afternoon. Meanwhile, hundreds of Riverside County firefighters were battling a 35-acre fire along the 15 Freeway in Temecula.

That fire temporary closed some lanes in the 15 Freeway as flames licked the roadway. An army of firefighters battled the blaze by air and on the ground. Some drivers reported being stuck in traffic for hours.

A low-pressure system that will cool the region is on its way, Sirard said.


“Today is the last day of really hot temperatures inland,” Sirard said. “We’ll still be above normal tomorrow,” he said, “just cooler.”

Sirard said he expects inland areas be five to eight degrees cooler on Sunday.

Areas such as downtown and the coast have suffered less than the foothills, mountains and deserts. Sirard said Saturday that downtown’s high temperature was about eight degrees above normal, but would not climb past the mid- to upper 80s. Along some beaches, temperatures could drop below average because of low, lingering clouds.

The gradual cooling that starts Sunday will continue throughout the week, bringing temperatures back to normal by Thursday or Friday, Sirard said.


The weather service has yet to issue any formal heat warnings or advisories because humidity has remained relatively low. Although he urged people to use common sense when dealing with the heat this weekend, Sirard said the most serious heat doesn’t usually strike Southern California until July or August.

ALSO

Meet the man who wants to restore native plants to a Laguna Beach hillside

Pearl Pinson’s backpack might hold clues as search for kidnapped teen continues


Quick action by professors kept UCLA gunman from escape and potentially shooting more people

matt.stevens@latimes.com

Twitter: @ByMattStevens

UPDATES:


3:39 p.m.: This article was updated with more details on fire.