Excessive Heat in Apple and Lucerne Valleys, California

A long-duration, excessive heat wave occurred across the High Desert from July 12-22. Highs reached the mid-90s to upper-100s each day. A brief downtrend in the highs occurred July 17-20 before ramping back up on July 21. The following are the highest temperatures reported during the event, and the day on which the peak temperature occurred:

Hesperia: 106 (7/15/23) Hesperia ranged from 102-106 through the first half of the event, with highs reaching the low-100s again by July 21.

Apple Valley: 110 (7/15/23) Anza ranged from 100-110 through the duration of the event.

A long duration heat wave impacted inland portions of Southern California July 7 to 29 with nearly continuous warnings and advisories. San Diego County public health reported 224 heat related incidents around their network of 23 hospitals. Numerous record highs were broken in the lower deserts where temperatures topped 115 for many days in a row, as well as across the inland valleys and mountains. Overnight low temperatures remained elevated in the lower deserts as lows only fell into the mid-80s to mid-90s, exacerbating the extreme heat risk.

July 2023 was the hottest month on record at Palm Springs.