Map of forecast high temperatures for Southern California for Monday Sep 21, 2026. For the coastal areas: 72 to 76, western valleys and inland Orange County: 75 to 80, inland valleys: 75 to 82, mountains between 4000 ft and 7000 ft: 67 to 80, high desert: 82 to 90, low desert: 95 to 100.
Data Courtesy of San Diego Weather Forecast Office
Evaporative Cooler Effectiveness
Outside Temp99°F
Dew Point45°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)
