Map of forecast high temperatures for Southern California for today Sep 20, 2026. For the coastal areas: 73 to 77, western valleys and inland Orange County: 76 to 81, inland valleys: 79 to 88, mountains between 4000 ft and 7000 ft: 74 to 84, high desert: 88 to 93, low desert: 97 to 101.
Data Courtesy of San Diego Weather Forecast Office
Evaporative Cooler Effectiveness
Outside Temp97°F
Dew Point48°F
Est. Output73°F
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.
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)
