September Weather in Decatur, United States

Last updated: June 24, 2025

The average temperature in Decatur, United States during September is a pleasant 24°C (75°F). Expect a minimum of 10°C (50°F) and a soaring maximum of 37°C (100°F). Be prepared for some rain, as precipitation averages 93 mm (3.7 in) over 9 days, coupled with a humidity level of 76%.

September Temperature in Decatur

In September in Decatur, the average temperature is 24°C (75°F), with maximums reaching up to 37°C (100°F) and minimums dropping as low as 10°C (50°F). Travelers should be prepared for warm days and cooler nights, making it ideal to pack layers for varying temperatures.

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 24°C (75°F), with highs reaching up to 37°C (100°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec434854607076807875655046
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 precipitation amount is 93 mm (3.7 in) over the course of 9 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 93 mm (3.7 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec981731621521201041081149312478133
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 76%. With an average temperature of 24°C (75°F), this humidity feels like a warm, enveloping blanket that clings to your skin, making outdoor activities feel a bit sluggish and urging you to seek shade and hydration.

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 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%82%85%85%83%76%76%80%88%88%
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 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36810111111109753
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 Weather6°C (43°F)98 mm (3.8 inches)86%moderate
February Weather9°C (48°F)173 mm (6.8 inches)86%high
March Weather12°C (54°F)162 mm (6.4 inches)86%very high
April Weather16°C (61°F)152 mm (6.0 inches)82%very high
May Weather21°C (71°F)120 mm (4.7 inches)85%extreme
June Weather24°C (76°F)104 mm (4.1 inches)85%extreme
July Weather27°C (80°F)108 mm (4.2 inches)83%extreme
August Weather26°C (79°F)114 mm (4.5 inches)76%very high
September Weather24°C (75°F)93 mm (3.7 inches)76%very high
October Weather18°C (65°F)124 mm (4.9 inches)80%high
November Weather10°C (51°F)78 mm (3.1 inches)88%moderate
December Weather8°C (47°F)133 mm (5.2 inches)88%moderate

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