California cities reported record temperatures this weekend as a punishing and dangerous heatwave only worsened in some areas Sunday.
The heat has already sparked damaging wildfires and stressed the state's power grid. Forecasters warn the sweltering temperatures also pose health risks as people celebrate the holiday weekend.
The northern half of the West Coast has been spared the worst of the heatwave, according to Sunday excessive heat warnings and heat advisories from the National Weather Service. Most of California and Nevada and parts of Arizona, Utah, Oregon and Idaho should brace for high temperatures, forecasters say.
Meanwhile, two dangerous wildfires are burning through the same California county Sunday, creating new challenges for firefighters.
The wind-driven Mill Fire, which started Friday about 250 miles north of San Francisco, has destroyed more than 100 homes in the small town of Weed, blazing through more than 4,200 acres and standing at 25% contained as of Sunday morning. Meanwhile, the nearby Mountain Fire close to the small community of Gazelle grew from Saturday night to Sunday morning, covering 6,451 acres at 5% contained.
How hot will it get Labor Day weekend?
The high temperatures are expected to continue in the Western U.S. through the holiday weekend and into the middle of the week.
Sunday's forecast called for San Diego to reach the low-to-mid 90s; Los Angeles to hit a high in triple digits; Palm Springs, Death Valley and Fresno to record highs well into the triple digits and Death Valley to approach 121 degrees at some point today, according to NWS.
"Highs in California will likely threaten monthly temperature records and be particularly dangerous for vulnerable residents," the Weather Service said Sunday.
Some cities have already seen daily record-breaking highs Sunday:
- Oxnard, Calif. hit 101 degrees, breaking its daily record of 96 set in 1961
- Camarillo, Calif. reached 103 degrees, exceeding its previous daily record by 10 degrees set in 1961
As coastal cities see record heat, hotter inland communities face mounting risk from the weather.
"Interior Northern California is now heading for a truly dangerous, searing heatwave," Daniel Swain, a climate scientist at the University of California, Los Angeles, tweeted Sunday. "All-time September records are now all but guaranteed in the Central Valley (on multiple consecutive days!), and all-time (any month) records now appear well within reach."
More:What is the hottest temperature ever recorded? Where on Earth was it?
Extreme heat dangers over holiday weekend
Some areas, including around Sacramento, were opening cooling centers and offering tips to avoid heat illness.
That includes staying hydrated, limiting sun exposure and avoiding the hottest part of the day. Officials urged residents to check on neighbors, beware of leaving pets or people in hot cars and make sure animals have shade and water.
And with California facing a drought as it enters what is traditionally the worst of the fire season, Cal Fire reminded residents to avoid any activity that could start a fire, noting that about 95% of wildfires are caused by humans.
More:West Coast heat wave: About 50 million people warned of extreme heat; wildfires prompt evacuations
Power grid update
State officials hope to avoid rolling blackouts by asking residents to voluntarily use less power, even as the heat tempts Californians to crank up their air conditioners.
The California Independent System Operator (ISO) extended its statewide Flex Alert into Sunday, calling for voluntary electricity conservation due to increasing heat, tightening energy supplies and more potential strain on the grid.
Gov. Gavin Newsom's office said in a statement that power demands this weekend were expected to be at the highest since the summer of 2017.
More:California hopes to avoid blackouts amid heat wave by asking millions of people to use less electricity
Contributing: Doyle Rice, USA TODAY; Jessica Skropanic and Jenny Espino, Redding Record Searchlight (Redding, Calif.); The Associated Press
Chris Kenning is a national news writer. Reach him at [email protected] and on Twitter @chris_kenning.
