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September Weather in Phoenix, United States

Last updated: June 24, 2025

In Phoenix, United States, the average temperature in September hovers around 18°C (65°F), with minimums dipping to 4°C (39°F) and maximums rising to a warm 32°C (91°F). During this month, expect about 87 mm (3.4 in) of precipitation spread over 10 days, contributing to an average humidity level of 78%. Stay prepared for a mix of mild temperatures and occasional showers!

September Temperature in Phoenix

In September in Phoenix, the average temperature is 18°C (65°F). Maximum temperatures can reach 32°C (91°F), while minimums can drop as low as 4°C (39°F). This varied climate makes Phoenix an ideal destination for travelers seeking both warm days and cool evenings.

September Weather in Phoenix: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Phoenix, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Phoenix, September typically has an average temperature of 18°C (65°F), with highs reaching up to 32°C (91°F) and lows dropping to around 4°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec272935455766737165554032
Data source: Temperature data for Phoenix generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Phoenix

In Phoenix in September, the precipitation amount is 87 mm (3.4 in) over the course of 10 days.

September Precipitation Trends in Phoenix

The chart displays monthly precipitation patterns in Phoenix, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Phoenix, September typically receives around 87 mm (3.4 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec97999112211910017512487170115114
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Phoenix

In Phoenix in September, humidity is 78%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket, making travel quite muggy and potentially uncomfortable, as it can leave you feeling sticky and fatigued more quickly than usual.

September Average Humidity in Phoenix

This chart illustrates the average monthly humidity levels in Phoenix, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Phoenix is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%87%88%82%79%78%76%78%84%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Phoenix

In Phoenix in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Phoenix.

Maximum UV Index Levels in Phoenix for September

The chart shows the monthly maximum UV Index (UVI) for Phoenix in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Phoenix typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3468910997632
Data source: Phoenix September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Phoenix Compares to Other Months

Weather in Phoenix varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Phoenix, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Phoenix, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)97 mm (3.8 inches)90%moderate
February Weather-2°C (29°F)98 mm (3.9 inches)90%moderate
March Weather1°C (35°F)91 mm (3.6 inches)87%high
April Weather7°C (46°F)122 mm (4.8 inches)88%very high
May Weather14°C (57°F)119 mm (4.7 inches)82%very high
June Weather19°C (67°F)100 mm (3.9 inches)79%very high
July Weather23°C (73°F)175 mm (6.9 inches)78%very high
August Weather22°C (72°F)124 mm (4.9 inches)76%very high
September Weather18°C (65°F)87 mm (3.4 inches)78%high
October Weather13°C (55°F)170 mm (6.7 inches)84%high
November Weather5°C (41°F)115 mm (4.5 inches)89%moderate
December Weather0°C (33°F)114 mm (4.5 inches)86%low

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