By Reginald Stanley. Posted August 23, 2026, 11:52 PM.

A strong ridge of high pressure over the Four Corners region is slated to bring dangerous heat to Southern California later this week, prompting the National Weather Service to issue both a Heat Advisory and Extreme Heat Watch this week.

Inland valleys baked in widespread triple-digit heat this weekend, with nearly every active WeatherCurrents station soaring past the century mark Sunday afternoon. Lake Elsinore was once again the hottest location in the WeatherCurrents lineup, with a high temperature of 112 degrees recorded there on Sunday. The current Heat Advisory in effect for areas away from the immediate coast, all the way to (and including) the mountains, is set to expire at 10 AM Tuesday morning. From that time, an Extreme Heat Watch will go into effect from Tuesday morning and last until Friday evening - and will affect not only the inland valleys, but also the mountains, high desert and even the immediate coasts(!). During this period, temperatures between 90 and 100 degrees are forecast for inland Orange County; 90 to 102 degrees in the San Diego County valleys; 100 to 108 degrees for the Inland Empire; and 89 to 101 degrees in the mountains. Nighttime temperatures will remain 5 to 10 degrees above average, providing little relief from the heat. Across the low deserts (including the Coachella Valley), an Extreme Heat Warning will also be in effect throughout the week, accompanied by temperatures between 110 and 117 degrees.

The National Weather Service advises people to stay indoors in an air-conditioned room when possible, drink plenty of fluids, stay out of the sun and check up on relatives and neighbors.