Intense summer heatwave with triple-digit temperatures sears Southern California

After experiencing severe pre-summer heat in Texas and Florida, California and Arizona are now bracing for temperature spikes. The National Weather Service predicts a heatwave throughout much of the Southwest and parts of California from Tuesday through Thursday due to a high-pressure ridge over the region.

Forecasts indicate temperatures could reach 113 degrees Fahrenheit in Phoenix and 108 in California’s Central Valley. “It’s coming early,” said Eric Kurth, a meteorologist with the National Weather Service in Sacramento, California. “Heat is here, and we need to prepare.”

By Wednesday, most Southwest communities will face moderate to extreme heat risks, according to the National Weather Service’s new heat risk map. High temperatures could also elevate fire risks. Already, a grass fire near Tracy, California, about 65 miles east of San Francisco, quickly expanded to over 14,000 acres, closed Interstate 580, and prompted evacuations. Cecile Juliette from Cal Fire reported strong winds making it difficult to stand.

This early fire activity is unusual, Juliette added: “We normally see more fires in July, August, September. People need to be ready to evacuate at a moment’s notice.” By Monday morning, firefighters had contained three-quarters of the blaze.

Kurth noted that the heatwave wouldn’t be uncommon for August in central California, but its early occurrence could be more impactful as “people aren’t adjusted to the heat.” He also warned of increased drowning risks in mountainous areas, as people flock to rivers with cold, fast-running snowmelt waters. “Be careful; wear life vests,” Kurth advised.

The National Oceanic and Atmospheric Administration predicted last month that 2024 will be among the five warmest years on record, with a decent chance to be the hottest. Last year, heat waves led to a spike in deaths across the South and Southwest. An Associated Press analysis found over 2,300 heat-related deaths in the U.S. last summer, the highest in 45 years. Heat often exacerbates conditions like heart disease, respiratory problems, or kidney disease, making its impact less obvious on death certificates. Texas A&M researchers estimated that 11,000 additional deaths occurred due to heat last year.

High-pressure ridges, like the one expected this week, were responsible for many of those deaths. The Phoenix area experienced temperatures above 110 degrees nearly every day in July last year, a phenomenon scientists attribute to climate change. Maricopa County, home to Phoenix, saw at least 645 heat-related deaths, a 52% increase from the previous year.