Extended California heat wave brings extreme health, fire risk; power shutoffs likely

Extended California heat wave brings extreme health, fire risk; power shutoffs likely

Grace Toohey

Authorities are warning of extreme health and wildfire risks across California this week, as the longest heat wave of the year is set to kick off Tuesday, bringing triple-digit temperatures, with little overnight cooling, to the vast majority of the state.

“This is really just a long-duration heat event that will provide little to no overnight [temperature] relief," said Antoinette Serrato, a National Weather Service meteorologist in Hanford, Calif. The heat wave is expected to bring dangerous temperatures through the Fourth of July holiday and into early next week in many areas, particularly across Northern California, the Central Valley and southwestern deserts, she said.

Much of Los Angeles County's inland valleys and mountains, including the San Fernando Valley and San Gabriel Mountains, are included in an excessive heat watch from Wednesday through Sunday, when high temperatures from 95 to 110 degrees are expected. However, Southern California's coastline should be largely spared from the worst of the heat.

He said the duration of the heat event, caused by a type of high-pressure system moving in from the Pacific known as a heat dome, and the lack of overnight cooling across such a widespread area "will amplify both human heat stress and wildfire risk."

On Tuesday, a combination of excessive heat is expected to overlap with a red flag warning — an alert for extreme fire weather — in parts of the northern San Francisco Bay Area and Sacramento Valley, raising concerns about potential fire starts. Low humidity, winds up to 30 mph and hot temperatures could create the perfect storm for wildfires, officials warned.

Pacific Gas & Electric Co., the state's largest utility, announced that power cuts were likely for Tuesday and Wednesday in some Northern California counties, "due to high winds and dry conditions," part of its safety shutoff program that aims to reduce the chance for accidental fire ignitions. The counties that could be affected on Tuesday are Colusa, Glenn, Lake, Napa, Shasta, Solano, Tehama and Yolo, according to the utility's website. Colusa, Glenn, Shasta and Tehama could see continued shutoffs Wednesday.