Phoenix weather in September
In September, Phoenix has an average high of 38 °C101 °F and an average low of 24 °C75 °F, with about 22 mm0.9 in of precipitation. It is the 4th warmest month of the year and ranks 6th for precipitation.
How September compares with other months
Compared with August, September is 3 °C5.4 °F cooler on average and drier by 11 mm0.4 in. Compared with October, September is 6.5 °C11.8 °F warmer on average and wetter by 8 mm0.3 in. Daylight lasts about 12.3 hours around the middle of the month. Average relative humidity is 31% and the average cloud amount 25%.
Is September a good time to visit Phoenix?
September is not among the most comfortable months by our comfort score: it is hot (average high 38 °C101 °F). The most comfortable months in Phoenix are November–March.
What to wear in September
For Phoenix in September, pack very light, breathable clothing, a sun hat and plenty of water.
September in nearby places
| Place | High °C°F | Low °C°F | Precip. mmin |
|---|---|---|---|
| Phoenix | 38101 | 2475 | 220.9 |
| Peoria | 38101 | 2475 | 170.7 |
| Mesa | 38100 | 2374 | 220.9 |
| Tucson | 3494 | 2169 | 411.6 |
| Yuma | 39102 | 2475 | 120.5 |
| Nogales | 3188 | 1763 | 512.0 |
| San Luis Río Colorado | 40103 | 2374 | 110.4 |
| Mexicali | 40104 | 2476 | 80.3 |
| Henderson | 3697 | 2171 | 90.3 |
Nearby places that are more than 1 °C1.8 °F warmer in September: Mexicali; cooler: Tucson, Nogales and Henderson.
Other months in Phoenix
- January19 °C67 °F / 6 °C42 °F
- February21 °C70 °F / 7 °C44 °F
- March26 °C78 °F / 10 °C50 °F
- April30 °C86 °F / 13 °C56 °F
- May35 °C96 °F / 18 °C65 °F
- June42 °C107 °F / 24 °C76 °F
- July42 °C107 °F / 28 °C83 °F
- August41 °C105 °F / 27 °C81 °F
- September38 °C101 °F / 24 °C75 °F
- October32 °C90 °F / 17 °C63 °F
- November25 °C77 °F / 11 °C51 °F
- December19 °C66 °F / 5 °C42 °F
Frequently asked questions
How warm is Phoenix in September?
In September the average high in Phoenix is 38 °C (101 °F) and the average low is 24 °C (75 °F).
Does it rain a lot in Phoenix in September?
On average about 22 mm (0.9 in) of precipitation falls in September; it ranks 6th of the 12 months.
Is September the warmest month in Phoenix?
No. The warmest month in Phoenix is July, with an average high of 42 °C (107 °F). The coldest month is December, with an average low of 5 °C (42 °F).
How long is the day in Phoenix in September?
In the middle of September the day in Phoenix lasts about 12.3 hours from sunrise to sunset. The value is calculated from the position of the city and the sun.
How humid is Phoenix in September?
The average relative humidity in September is about 31%. This is a long-term average for the whole day.
How cloudy is Phoenix in September?
On average about 25% of the sky is covered by cloud in September. This is the mean cloud amount from satellite data, not the number of sunny days.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 494 m, while Phoenix lies at about 331 m. Temperatures on this page were therefore adjusted by +1.1 °C1.9 °F using the standard lapse rate of 6.5 °C per 1,000 m.