Map of forecast high temperatures for Southern California for Sunday Sep 20, 2026. For the coastal areas: 75 to 81, western valleys and inland Orange County: 79 to 84, inland valleys: 85 to 90, mountains between 4000 ft and 7000 ft: 75 to 83, high desert: 86 to 91, low desert: 98 to 103.
Data Courtesy of San Diego Weather Forecast Office
Evaporative Cooler Effectiveness
Outside Temp82°F
Dew Point55°F
Est. Output69°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)
