Warm weather arrives this week in Southern California as extreme heat builds up across much of the southwestern United States. An Extreme Heat Warning has been issued for the deserts of San Diego County, with daytime high temperatures ranging from 108 to 113 degrees Fahrenheit each afternoon through Friday evening.

The hottest days are expected to be Thursday and Friday. This is due to a high-pressure ridge expanding over the region, promoting drier, warmer, and clearer conditions. In San Diego County, coastal clouds will persist as the marine layer rebuilds each morning and night, keeping temperatures around normal. Clouds have extended into the valleys this morning and will gradually retreat each morning and midday. Daytime high temperatures will be near or slightly above seasonal, with temperatures in the low 70s along the coast and in the high 70s to low 80s in the inland valleys.

The heat will be felt east of the valleys, especially towards the mountain and desert microclimates. The deserts of San Diego County will experience dangerously hot conditions with temperatures from 108 to 113 degrees starting Wednesday. This change comes after weeks of similar daily conditions. Now, a high-pressure ridge will strengthen over the region this week. As a result, temperatures will rise in both San Diego County and the southwestern United States, especially from Wednesday through Saturday.

It is important to recognize the significance of staying cool in extreme heat. Each year, heat-related deaths surpass all other weather-related deaths, including those from tornadoes, floods, and hurricanes. This is largely because heat cannot be seen in the same way as other weather hazards. Therefore, it is especially important to heed expert warnings, including staying hydrated and avoiding strenuous outdoor activities.