Heat wave hits Southern California with a scorching Fourth of July weekend

After months of persistently overcast skies and cooler conditions, Southern and Central California are set to see some of their highest temperatures of the year this weekend.

Forecasters issued warnings of excessive, dangerous heat throughout the valleys, deserts and foothills from San Diego County up to Mariposa County, with little relief expected in the evenings.

“The most extreme conditions will be in the Antelope Valley,” David Gomberg, a meteorologist with the National Weather Service office in Oxnard, said Friday. “The desert regions are going to be hottest. We’re going to have a sharp rise today, but the hottest temperatures will be tomorrow and Sunday.”

Lancaster and Palmdale are forecast to hit highs of 107 and 110 over the weekend, and much of the foothills in Los Angeles, Ventura and San Bernardino counties are expected to reach triple-digit temperatures. The Santa Clarita Valley should expect highs up to 105, Gomberg said.

An excessive heat warning will be in effect Saturday and Sunday for the Santa Clarita and Antelope valleys, warning that the hot and dry weather “will significantly increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities,” according to the National Weather Service.

Overnight lows in many places are forecast to cool only into the 70s, which can create dangerous conditions, especially for those without air conditioning or certain health conditions.

Downtown Los Angeles will reach the 80s for the first time in months, snapping a historic streak of 60 straight days without crossing that threshold — the longest on record for May and June. But it might not happen until the weekend; the expected high Friday for downtown L.A. is 79 degrees.

“It’s going to be a pretty close call today,” Gomberg said. “There’s a chance today, but likely over the weekend.”

Downtown L.A. is forecast to reach into the low 80s this weekend, and highs along the coast should remain in the 70s. Conditions a few miles inland will be drastically warmer, with Burbank expected to reach the upper 90s.

The heat wave, however, is hitting the Central Valley first, with an excessive heat warning already in effect Friday morning until late Sunday for much of the area, including the San Joaquin Valley, Kern River Valley, Indian Wells Valley, the lower Sierra Nevada foothills and much of the Mojave desert. Temperatures across the region there are expected to reach well into the 100s, even as high as 112.

The worst of the heat is expected to be short-lived, with slightly lower temperatures expected by the Fourth of July, Gomberg said.

Monday will still be very warm over the interior but not quite as hot as the weekend, with most places forecast to see a temperature drop of about 5 degrees by Monday.

“Fourth of July itself we’ll see further cooling, returning closer to normal for this time of the year,” Gomberg said. Most of the high deserts and foothills are forecast to drop into the 90s.

But even as temperatures fall, he said, there is a growing concern about wildfires from Friday through at least Tuesday, with low humidity, high temperatures and more activity from the holiday weekend, including fireworks and sparklers.

“There is an elevated threat for larger fires,” Gomberg said.