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September Weather in Decatur, United States

Last updated: June 24, 2025

In September, the average temperature in Decatur, United States hovers around 19°C (66°F). Expect to experience a range from a brisk minimum of 2°C (36°F) to a warm maximum of 33°C (92°F). With an average humidity of 79%, you'll want to prepare for some moisture in the air. Additionally, be ready for 118 mm (4.6 in) of precipitation spread over 10 days, making it wise to carry an umbrella on your adventures!

September Temperature in Decatur

In September in Decatur, 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 (36°F). This diverse climate makes Decatur an ideal destination for travelers looking to experience a range of temperatures and activities.

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

The chart illustrates September temperature patterns in Decatur, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Decatur, 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 (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec222337476071757266523730
Data source: Temperature data for Decatur 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 Decatur

In Decatur in September, the total precipitation amount is 118 mm (4.6 in) over a span of 10 days.

September Precipitation Trends in Decatur

The chart displays monthly precipitation patterns in Decatur, 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 Decatur, September typically receives around 118 mm (4.6 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec55545997136124781061181134349
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Decatur

In Decatur in September humidity is 79%. With an average temperature of 19°C (66°F), this humidity feels like a warm embrace, making it feel much warmer than the actual temperature and creating a heavy, sticky atmosphere that can be a bit uncomfortable for traveling.

September Average Humidity in Decatur

This chart illustrates the average monthly humidity levels in Decatur, 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 Decatur is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%85%85%85%78%80%78%76%79%83%88%82%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Decatur

In Decatur in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Decatur.

Maximum UV Index Levels in Decatur for September

The chart shows the monthly maximum UV Index (UVI) for Decatur 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 Decatur typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098532
Data source: Decatur 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 Decatur Compares to Other Months

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

This table compares monthly weather conditions in Decatur, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (22°F)55 mm (2.2 inches)85%moderate
February Weather-5°C (24°F)54 mm (2.1 inches)85%moderate
March Weather3°C (37°F)59 mm (2.3 inches)85%high
April Weather8°C (47°F)97 mm (3.8 inches)85%very high
May Weather16°C (60°F)136 mm (5.3 inches)78%very high
June Weather22°C (71°F)124 mm (4.9 inches)80%very high
July Weather24°C (75°F)78 mm (3.1 inches)78%very high
August Weather22°C (72°F)106 mm (4.2 inches)76%very high
September Weather19°C (66°F)118 mm (4.6 inches)79%very high
October Weather11°C (52°F)113 mm (4.5 inches)83%moderate
November Weather3°C (37°F)43 mm (1.7 inches)88%moderate
December Weather-1°C (30°F)49 mm (1.9 inches)81%low

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