San Diego Scorches Under Extreme Heatwave, Monsoon Storms Loom

San Diego County is currently battling a relentless heatwave, with temperatures projected to climb significantly higher throughout the week. A stubborn ridge of high pressure, firmly parked over the Southwest, is the primary driver, keeping conditions a scorching 5 to 10 degrees Fahrenheit above the typical average. This brutal heat is not expected to offer any relief until at least Friday, August 28, 2026.

The National Weather Service (NWS) San Diego CA issued an Extreme Heat Warning on August 22, 2026, at 1:10 PM PDT, which is slated to remain in effect until August 28, 2026, at 8:00 PM PDT. This critical alert highlights dangerously hot conditions, with some areas potentially reaching a staggering 117 degrees Fahrenheit. The NWS indicates that the risk levels for this period range from major to extreme across the county.

Initially, a heat advisory was in place for inland valleys and mountains, lasting through Tuesday morning, August 25, 2026. However, a more severe watch was anticipated to begin on Tuesday, August 25, 2026, extending through Friday evening, August 28, 2026. This expanded watch notably includes coastal communities, which typically avoid the most intense heat, signaling the widespread nature of the current conditions. Deserts within the county, always prone to extreme temperatures, remain under an extreme warning through Friday night, August 28, 2026.

Reports from August 19, 2026, had already indicated the formation of a high-pressure "heat dome" that would expand westward, setting the stage for these warmer days. This expansion was expected to bring a resurgence of monsoonal moisture, with temperatures trending up to 8 degrees above average. Desert areas, in particular, were forecast to consistently exceed 110 degrees Fahrenheit for most of the week, a prediction that has largely held true.

Monsoon moisture, initially limited, is gradually making its return to the region. While the weekend of August 22-23, 2026, remained largely dry for most of San Diego County, with only sporadic mountain showers and widespread thunderstorm development deemed unlikely, the situation shifted. By Monday, August 24, 2026, the monsoonal flow was expected to introduce a slight chance of isolated afternoon showers and storms over the mountains and adjacent deserts, with these probabilities modestly increasing later in the week.