Phoenix Az Weather September 2024. Daily low temperatures decrease by 10°f, from 81°f to 72°f, rarely falling below 65°f or exceeding 87°f. In phoenix, the average temperature for september is around 87.3°f (30.7°c), with highs reaching up to approximately 99.5°f (37.5°c).

Focused daily weather, temperature, sunrise, sunset, and moonphase forecasts. Get the monthly weather forecast for phoenix, az, including daily high/low, historical averages, to help you plan ahead.