Thunderstorms may cool ‘heat dome,’ but hot weather will be back in SoCal this weekend

Southern California will see cooler temperatures and possibly thunderstorms this week, getting a reprieve from the “heat dome” that has broiled the region for weeks.

But the relief won’t last long. Temperatures are expected to heat back up over the weekend.

This week through Wednesday and Thursday, high temperatures are expected to be in the 80s for downtown Los Angeles and the mid-80s to mid-90s in the valleys, according to the National Weather Service. But temperatures will likely warm up to around the mid-to-upper 90s and toward 100 over the weekend, with the Antelope Valley possibly seeing highs up to 105 degrees.

High pressure has remained situated over the Southwest for the past few weeks, resulting in a persistent heat dome over Southern California, leading to record high temperatures.

The heat wave was “unusual in the sense of how long it’s lasted” and “in the wide area that it covers,” according to National Weather Service meteorologist David Sweet.

There’s a chance for showers and thunderstorms for the coasts and valleys in Los Angeles County until noon Monday, Sweet said. There’s moisture instability resulting from monsoonal flows pushing into San Diego and Orange counties. There’s a 20% chance of showers near Los Angeles County’s borders with Orange and Riverside counties through Monday afternoon and into the evening.

Monday marks the last day of elevated wildfire conditions, according to Sweet. While fuel moisture — how much water brush and vegetation have left —remained about 100% through May and June, levels have gone down to 80% to 90% during the recent heat wave.

As the levels drop, the vegetation can serve as fuel for fires. “Critical” conditions are when the levels drop to around 60%, which is usually reached in July and continue through November.

“It’s getting to the point where fires are becoming more of a concern,” Sweet said.

Several fires have broken out across Southern California during the record-breaking heat and low humidity levels.

The York fire, which had scorched 77,000 acres and was 9% contained Monday morning, first sparked near the New York Mountains in the Mojave National Preserve in eastern San Bernardino County before spreading into Nevada on Sunday.

The Bonny fire also ignited last week near Aguanga east of Temecula and was 5% contained as of Saturday, according to the California Department of Forestry and Fire Protection and the Riverside County Fire Department.

The heat wave has been roasting a large section of the country. At Zion National Park in Utah, park staff left chocolate chip cookie dough on a car’s dashboard over the weekend to see if it would bake. Temperatures have been staying in the triple digits over the past few weeks, meaning that it can reach up to 200 degrees inside a vehicle.

“Your car can feel like an oven in the Zion heat — literally — Which is why we decided to bake some cookies!” the park service said in an Instagram post.

The cookies took about three hours to bake. Before putting the baking sheet in, park staff placed a thermometer inside the car to measure how hot it was. The device later melted.