Southland continues to perspire as heat wave persists

A persistent heat wave will continue Monday across Southern California, with peak temperatures reaching triple digits in the valleys and some mountain regions, and little to no relief in sight through next weekend.

“Dangerously hot temperatures are expected across the interior through at least today and possibly Tuesday as strong high pressure remains over the West Coast,” according to the National Weather Service. “Onshore flow and a shallow marine layer will keep areas near the coast much cooler, but still above normal. A slight cooling trend is expected through the middle of the week, however warmer temperatures are expected for the latter half of the week as the high pressure ridge returns.”

The hot, dry weather was creating wildfire danger across Southern California, with four brush fires burning in Riverside County and Los Angeles County officials keeping a close eye on the Angeles National Forest and other vulnerable sites.

Firefighters from Utah and Colorado have been called upon to help LA County officials with any potential brush fire response, the Angeles National Forest tweeted Sunday.

Forecasters said the heat wave is likely to last, prompting elevated fire weather conditions existing through next weekend in the interior valleys, lower mountains and deserts — with brief critical fire weather conditions across the Antelope Valley and foothills.

Temperatures reached 109 degrees in Palmdale and Lancaster on Sunday, 102 in Santa Clarita, 100 in Northridge, 97 in Van Nuys, 91 in Pasadena and 87 in downtown Los Angeles.

Excessive heat warnings were in effect until at least 11 p.m. Monday in the San Gabriel Mountains and the Santa Clarita and Antelope Valleys. Less serious heat advisories were in effect for the same period in the San Gabriel and San Fernando valleys.

Temperatures were only expected to drop a couple degrees midweek, but generally similar highs were forecast for the rest of the week, with next weekend’s highs even possibly exceeding this weekend’s numbers, according to the NWS.

Cooling centers were open across Los Angeles during the heat wave for those with no access to air conditioning. Angelenos can find a nearby cooling spot using the city’s Cool Spots LA App at bit.ly/CoolSpotsLA. City emergency officials announced Sunday that hours at the centers were extended until 9 p.m. Monday.

Most centers are served by one or more LA Department of Transportation Dash and Metro bus lines. Details are available at https://emergency.lacity.gov.

Information on Los Angeles County cooling centers can be found at ready.lacounty.gov/cooling-centers-copy-copy.

“Extreme heat will significantly increase the potential for heat- related illnesses, particularly for those working or participating in outdoor activities,” NWS forecasters warned. “Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances.”

The high heat was expected to contribute to “elevated to brief critical fire conditions” in desert, mountain and interior valley areas. Those areas will see humidity levels in the 5% to 15% range. Winds are expected to be relatively light, but some higher gusts are possible in traditionally wind-prone areas.

Temperatures in Orange County were slightly better on Sunday, reaching the upper 80s and low 90s inland.

As a result of the Riverside County fires, the South Coast Air Quality Management District issued a smoke advisory that was later extended through at least noon Monday.

AQMD officials urged people to limit exposure by remaining indoors with windows and doors closed, avoiding strenuous physical activity, using air conditions rather than swamp coolers or fans that bring in outside air, avoiding burning wood in fireplaces and fire pits, and wearing respirator masks while outdoors.

Another day of “dangerously hot conditions” is on tap Monday for the Riverside region — especially the deserts — with high temperatures ranging from 100 to 113, according to the National Weather Service.

The days-long heat wave — courtesy of a persistent high-pressure system — peaked Sunday, creating potentially dangerous and unhealthful conditions.

“Strong high pressure aloft will maintain hot weather inland into next week, with periods of high clouds,” according to the National Weather Service. “Breezy west to southwest winds near the passes will keep fire weather conditions elevated.”

Excessive heat warnings will be in place until 11 p.m. Wednesday in the Coachella Valley and the San Gorgonio Pass, where high temperatures of 115 to 121 degrees are possible.

A similar warning will be in place until 8 p.m. Tuesday in the Riverside County Mountains and valleys, with highs possibly reaching 105 degrees in the mountains and up to 110 elsewhere.

“The peak of the heat is expected this weekend with slight cooling for early next week,” according to the NWS. “High temperatures near 115 degrees could continue through the week.”

Meanwhile, many Southland beaches remain mired in morning low clouds and fog, with daytime temperatures in the upper 70s and 80s — making those areas popular destinations this weekend.

Updated July 17, 2023, 11:12 a.m.

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