What’s a heat dome? Weather phenomenon leaves California sweltering

Blistering high temperatures are breaking records across California, and it’s all the fault of a heat dome over the Golden State, experts say.

All-time heat records were tied or broken Tuesday, Sept. 6, in Santa Rosa, Napa, Livermore, Redwood City, San Jose and King City in the San Francisco Bay Area, the National Weather Service said.

Temperatures in Livermore and King City reached 116 degrees, the NWS reported. Sacramento also broke its record at 116 degrees.

California as a whole narrowly escaped rolling blackouts on Tuesday as the power grid sagged, although four cities did experience rolling blackouts because of miscommunications, The Sacramento Bee reported.

Rolling blackouts are also a possibility Wednesday, Sept. 7, as high temperatures continue.

Here’s what to know:

What’s a heat dome?

Heat domes can bring about extreme heat waves and are typically triggered by a “strong change in ocean temperatures from west to east in the tropical Pacific Ocean,” according to the National Oceanic and Atmospheric Administration.

That steamy air becomes trapped under a dome-like area of high pressure, causing “vast areas of sweltering heat,” the agency said.

“As prevailing winds move the hot air east, the northern shifts of the jet stream trap the air and move it toward land, where it sinks, resulting in heat waves.”.

How long will the heat last?

100-plus temperatures are expected to run through Friday, Sept. 9, The Sacramento Bee reported.

The heat dome will begin to break up then, lowering temperatures, an NWS forecast said.

This story was originally published September 7, 2022 at 10:44 AM with the headline "What’s a heat dome? Weather phenomenon leaves California sweltering."