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September Weather in Ann Arbor, United States

Last updated: June 24, 2025

In September, the average temperature in Ann Arbor, United States hovers around 19°C (66°F), with minimums dipping to 2°C (35°F) and maximums climbing up to 33°C (92°F). Expect around 67 mm (2.6 in) of precipitation spread over 9 days, contributing to an average humidity of 80%.

September Temperature in Ann Arbor

In September in Ann Arbor, the average temperature is 19°C (66°F). The maximum can reach 33°C (92°F) and the minimum can be as low as 2°C (35°F). This mild climate makes Ann Arbor a great destination for travelers seeking a pleasant escape during this time of year.

September Weather in Ann Arbor: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Ann Arbor, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ann Arbor, September typically has an average temperature of 19°C (66°F), with highs reaching up to 33°C (92°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec272837476070747266543932
Data source: Temperature data for Ann Arbor 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 Ann Arbor

In Ann Arbor in September, the total precipitation amount is 67 mm (2.6 in), occurring over a span of 9 days.

September Precipitation Trends in Ann Arbor

The chart displays monthly precipitation patterns in Ann Arbor, 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 Ann Arbor, September typically receives around 67 mm (2.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec64677789121879772671027753
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Ann Arbor

In Ann Arbor in September humidity is 80%. With an average temperature of 19°C (66°F), this humidity feels like a warm, thick blanket wrapping around you, making outdoor activities feel more strenuous and sticky, which can ultimately dampen the experience of traveling.

September Average Humidity in Ann Arbor

This chart illustrates the average monthly humidity levels in Ann Arbor, 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 Ann Arbor is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%85%86%80%80%80%81%80%84%90%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Ann Arbor

In Ann Arbor 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 Ann Arbor.

Maximum UV Index Levels in Ann Arbor for September

The chart shows the monthly maximum UV Index (UVI) for Ann Arbor 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 Ann Arbor typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24599101097542
Data source: Ann Arbor 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 Ann Arbor Compares to Other Months

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

This table compares monthly weather conditions in Ann Arbor, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)64 mm (2.5 inches)88%low
February Weather-2°C (28°F)67 mm (2.6 inches)87%moderate
March Weather3°C (37°F)77 mm (3.0 inches)85%moderate
April Weather8°C (47°F)89 mm (3.5 inches)86%very high
May Weather15°C (60°F)121 mm (4.8 inches)80%very high
June Weather21°C (70°F)87 mm (3.4 inches)80%very high
July Weather24°C (75°F)97 mm (3.8 inches)80%very high
August Weather22°C (72°F)71 mm (2.8 inches)80%very high
September Weather19°C (66°F)67 mm (2.6 inches)80%high
October Weather12°C (54°F)102 mm (4.0 inches)84%moderate
November Weather4°C (39°F)77 mm (3.0 inches)89%moderate
December Weather0°C (33°F)53 mm (2.1 inches)86%low

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