Starting Friday, a heat wave has been set to bring misery to almost the entire length of California.
Triple girders are expected to rise and fall across the state, pushing record-level temperatures for the first time this year. Over the course of the two-day heatwave, heat recommendations are effective in large zones of the region, and thunderstorms could occur near the Nevada border in the Reno region.
Find Northern and Southern California advisories, including the Bay Area, Central Valley, and Central Coast.
On Friday, temperatures in Southern California were in the usual 8-16 degrees Celsius, with 90s highs rising just above the valleys, the mountains below and the desert, according to the National Weather Service’s Oxnard office.
“By Friday, levels will reach ‘major (red)’ in many regions. In other words, heat affects people who don’t have effective cooling or proper hydration,” the National Weather Service posted on X.
By Friday and Saturday, daily high temperatures will begin to push record levels during this period in parts of the western US on these maps. This displays NWS Heatrisk, an experimental color and quantity index that provides predicted heat-related risks. pic.twitter.com/nr3yljh10s
– National Weather Service (@NWS) May 27, 2025
In Los Angeles County, the Public Health Department has issued heat advisories to residents in the western and eastern regions of the San Fernando Valley, and the Santa Clarita Valley is warning of high-risk risks for the sensitive population of adults over the age of 65, children and adults with chronic illnesses. Forecasters expect temperatures to reach 100 degrees.
According to the Sacramento office of the National Weather Service, “dangerous hot conditions” are expected from the Lake Shasta area to the Sacramento Valley, with temperatures ranging from 99 to 107 degrees Celsius. The Mendocino region may have burning temperatures between 102 and 105.
Along the central coast, thermometers could reach 100, with severe fever expected in the city of Robull in Paso. Locals and tourists headed to the Kuyama Valley, the southern Salinas Valley, or the mountains and valley areas of San Luis Obispo County.
Temperatures in parts of Central California, including Mercedo, Madera, San Joaquin Valley, Fresno, Yosemite Valley and Sierra Foothills, are forecast to be 106.
Extreme heat warnings are also effective in Death Valley where temperatures are expected to exceed 115 degrees.
Reno’s National Weather Service issued a Fire Weather Watch from Saturday morning to Sunday evening to Sunday evening due to windy winds, low humidity and possible dry lightning. Mainly in the Sierra, there is a 10% to 15% chance of isolated dry thunderstorms with unstable gusts.
Temperatures across California are expected to begin falling from Saturday, with the forecaster saying the maximum temperatures occurring in Southern California, south of the Point Concept. Additionally, precipitation at San Gabriel Mountains could be around 10% to 15% on Saturday afternoon.
Also on Saturday, Tropical Storm Albin approaches the southern tip of the Baja Coast, pouring tropical moisture into San Diego and other parts of Southern California. South of Point Conception, there is a 10% to 20% chance of showers until Sunday night, predictors say.
How to protect yourself during a heat wave
For residents living in areas with extreme heat recommendations from the public, health officials advise you:
Drink lots of liquids. If possible, stay in an air-conditioned room. Check out your relatives and neighbors. If you need to be outside, wear lightweight, loose clothing and hats and use an umbrella. Don’t go out during the hottest times of the day. Stay in shaded areas as much as possible. Do not let pets or children go to the car. Even if the windows are broken or open, the car gets very hot inside, officials said.
If you don’t have air conditioning or a cool environment, Los Angeles County has a free cooling center, splash pads and community pools. You can find which cooling centers are nearby by searching for relief from the thermal section of the Raid LA County website.
Public health officials say heat-related illnesses such as fatigue and heat stroke will increase significantly during extreme heat.
Symptoms of fever-related illnesses include vomiting, dizziness, confusion, hot, red, dry, or damp skin. If you are seeing or experiencing these symptoms, move to a cool place and call 9-1-1.
