By Reginald Stanley. Posted August 19, 2026, 11:34 PM.

A heat advisory issued by the National Weather Service for the interior valleys of Southern California, is set to expire at 8 PM Thursday evening.

Temperatures soared again Wednesday across the region, with eight out of eleven active WeatherCurrents stations reaching or exceeding 100 degrees Wednesday afternoon. Lake Elsinore topped out at 112 degrees, the hottest temperature in the WeatherCurrents network for Wednesday. Most other stations in the network recorded high temperatures between 100 and 106 degrees, while WeatherCurrents stations in Fallbrook, Simi Valley and Pinon Hills only remaining slightly less hot. Across the San Bernardino and Riverside County valleys, high temperatures similar to Wednesday's are forecast again for Thursday. The deserts, mainly east of the San Jacinto Mountains (including eastern San Bernardino County) remain under an extreme heat warning through 8 PM Friday. Monsoonal moisture is forecast to increase during Thursday and Friday, raising chances of afternoon showers and thunderstorms for the mountains and deserts.

The National Weather Service advises the public to stay hydrated, avoid the outdoors during peak heat hours if possible, stay in an air-conditioned room, and check on neighbors and relatives.