By Reginald Stanley. Posted July 13, 2026, 10:11 PM.

Temperatures are forecast to soar across Southern California this week, nearing triple-digits inland through at least Thursday, as multiple rounds of monsoonal moisture surge into the region due to high pressure over the central Rocky Mountains.

The primary areas of focus during this week's monsoonal moisture are the mountains and deserts, with lower chances of thunderstorm activity making it west of the mountains. WeatherCurrents stations in Anza, East Hemet and Pinon Hills all recorded light measurable precipitation Monday afternoon, sprinkles briefly fell in other inland valley communities. After Monday, monsoonal moisture will decrease across the region Tuesday and Wednesday, before returning for Thursday and Friday. Increased humidity is also resulting in warmer overnight temperatures, offering little relief from the daytime heat. In addition, the National Weather Service has issued an Extreme Heat Warning for all inland, mountain and desert areas of the region from 10 AM Wednesday through 8 PM Thursday evening, while a Heat Advisory was similarly issued for coastal areas. Across inland Orange and San Diego counties, widespread high temperatures well into the 90s are expected later this week, while the inland valleys of Riverside and San Bernardino counties are expected to experience temperatures exceeding 100 degrees.