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September Weather in Decatur, United States

Last updated: June 24, 2025

In Decatur, United States, the average temperature in September reaches a warm 26°C (78°F). Daily temperatures can vary, with a minimum of 10°C (50°F) and a peak of 37°C (100°F). Be prepared for some rain, as the region experiences an average precipitation of 81 mm (3.2 in) over 7 days. The average humidity is around 64%, making it a comfortable yet humid month.

September Temperature in Decatur

In September in Decatur, the average temperature is 26°C (78°F). The maximum can reach 37°C (100°F), while the minimum can drop to as low as 10°C (50°F). It's advisable to pack both light clothing for the daytime heat and warmer layers for cooler evenings during your travels.

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 26°C (78°F), with highs reaching up to 37°C (100°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec454859647481858478665550
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 81 mm (3.2 in) over a period of 7 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 81 mm (3.2 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec51788591135864482811215049
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 64%. With an average temperature of 26°C (78°F), this humidity feels like a warm, thick blanket enveloping you, making travel slightly uncomfortable as you navigate the sticky air, leaving you yearning for a refreshing breeze or a cool drink.

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 64%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec77%76%74%75%80%80%75%67%64%70%82%85%
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 reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more 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 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101111111110864
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 Weather7°C (45°F)51 mm (2.0 inches)77%moderate
February Weather9°C (48°F)78 mm (3.1 inches)76%high
March Weather15°C (59°F)85 mm (3.3 inches)74%very high
April Weather18°C (64°F)91 mm (3.6 inches)75%very high
May Weather23°C (74°F)135 mm (5.3 inches)80%extreme
June Weather27°C (81°F)86 mm (3.4 inches)80%extreme
July Weather29°C (85°F)44 mm (1.7 inches)75%extreme
August Weather29°C (84°F)82 mm (3.2 inches)67%extreme
September Weather26°C (78°F)81 mm (3.2 inches)64%very high
October Weather19°C (67°F)121 mm (4.8 inches)70%very high
November Weather13°C (55°F)50 mm (2.0 inches)82%high
December Weather10°C (50°F)49 mm (1.9 inches)85%moderate

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