Map of forecast high temperatures for Southern California for Thursday Sep 24, 2026. Above average temperatures and muggy coastal conditions return through Sunday. Highs peak Wednesday in the Inland Empire, reaching the mid-to-upper 90s, then peak Fri/Sat for areas closer to the coast (mid-80s to low-90s).
Data Courtesy of San Diego Weather Forecast Office
Evaporative Cooler Effectiveness by City
Thousand Palms
Outside Temp101°F
Dew Point47°F
Est. Output75°F
Updated: Sep 23, 2:27 PM PDT
Palm Desert (Hwy 111 & El Paseo)
Outside Temp103°F
Dew Point48°F
Est. Output76°F
Updated: Sep 23, 2:23 PM PDT
Palm Springs Airport
Outside Temp102°F
Dew Point37°F
Est. Output72°F
Updated: Sep 23, 1:53 PM PDT
Thermal Airport
Outside Temp103°F
Dew Point44°F
Est. Output75°F
Updated: Sep 23, 1:52 PM PDT
How to Read This
Score
0–100, based on the wet-bulb depression — how much cooler the air could get versus the actual outside temperature. Drier air means more room to cool, so a bigger gap scores higher.
Wet-Bulb Depression
The gap between the outside (dry-bulb) temperature and the wet-bulb temperature — the coolest evaporation alone could get the air. A bigger gap means drier air and more room for the cooler to work with.
Estimated(Est.) Output
The approximate temperature of the air coming out of the cooler, estimated by cooling the outside temperature most of the way toward the wet-bulb temperature.
Efficiency
These numbers assume 80% saturation efficiency — typical for a well-maintained direct (single-stage) evaporative cooler.
Lower dew point + higher temp = better cooling
(This guide generally will work for misting systems also)
