Areas of Dangerous Heat and Severe Thunderstorms

Dangerous heat will persist across the Southwest U.S. through Friday with daytime highs of 110-115°F. Heat across the southern Plains will briefly ease to near-normal by late week before returning over much of the Plains into next week. Scattered strong to severe thunderstorms are possible across parts of the Northeast U.S. on Thursday. Damaging wind, hail, and a tornado or two are possible. Read More >

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Last Map Update: Wed, Aug 26, 2026 at 10:12:09 pm PDT

Watches, Warnings & Advisories

National Weather Service San Francisco Bay Area, CA

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National Weather Service Los Angeles, CA

Extreme Heat Warning

Red Flag Warning

Heat Advisory

Small Craft Advisory

Air Quality Alert

Air Quality Alert for Merced County

Friday Thunderstorm Probabilities

Widespread Moderate Heat Risk

Desert Extreme Heat Warning

Triple Digit Heat Continues

The Valley Air District has issued an Air Quality Alert for Merced County from Tuesday morning at 10:30AM through 11:00AM Thursday morning due to smoke from a local fire. Exposure to particle polluction can cause serious health problems; aggrevate lung disease, cause asthma attacks and acutre bronchitis and increase risk of respiratory infections. In people with heart disease, short-term exposure to particle pollution has been liked to heart attacks and arrhythmias accourding to the US Environmental Protection Agency. Children and elderly people are also more susceptible to consequences of high particulate levels. Stay indoors if possible. Avoid prolonged or strenuous outdoor physical activities to reduce the affect of unhealthy air. For current air quality conditions, go to fire.airnow.gov.

An influx of moisture from Tropical Storm Iselle will bring rain and thunderstorms into the Sierra Nevada and the northern San Joaquin Valley later this week and into the weekend ⛈️! Currently, the best chances of rain are in the foothills and the Sierra Nevada, but there is up to a 10% chance of at least 0.10" of rain in Fresno ☔. Remember that when thunder roars to go indoors!

(Updated 8/23 4:30 PM) - Widespread Moderate Heat Risk is expected across the San Joaquin Valley and adjacent lower foothills (including Lake Isabella) as temperatures range from 100 to 104 degrees from Monday through at least Wednesday. Moderate Heat Risk affects those who are sensitive to heat, especially those without cooling/hydration, and some health systems and industries. A Heat Advisory has been issued for the southern San Joaquin Valley valid from Monday through late Wednesday evening.

Widespread Moderate to Major Heat Risk is expected across the Mojave Desert as temperatures reach up to 108 degrees from Monday through at least Wednesday. Morning low temperatures between 75 and 80 degrees will provide little overnight relief from the heat. This level of heat brings a Major Risk of heat-related illnesses for much of the population, especially those without effective cooling or hydration.

The high pressure ridge will once again sit itself over the West Coast this week. With that, max temperatures will range from 100 to 104 degrees across the San Joaquin Valley, Lower Foothills and the Mojave Desert. Best chances for the heat will be through Wednesday, followed by a return to seasonally average temperatures to end this week.