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December Weather in Decatur, United States

Last updated: June 24, 2025

In December, the average temperature in Decatur, United States hovers around 2°C (36°F). Be prepared for a range in temperatures, with minimums plunging to -20°C (-3°F) and maximums reaching up to 19°C (66°F). Expect about 53 mm (2.1 in) of precipitation over 7 days, contributing to a notably high average humidity of 87%.

December Temperature in Decatur

In December in Decatur, the average temperature is 2°C (36°F), with maximums reaching 19°C (66°F) and minimums dropping as low as -20°C (-3°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December 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, December typically has an average temperature of 2°C (36°F), with highs reaching up to 19°C (66°F) and lows dropping to around -20°C (-3°F).
JanFebMarAprMayJunJulAugSepOctNovDec293243526575777470574236
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.

December Precipitation in Decatur

In Decatur in December, the total precipitation amount is 53 mm (2.1 in) spread over a period of 7 days.

December Precipitation Trends in Decatur

The chart displays monthly precipitation patterns in Decatur, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Decatur, December typically receives around 53 mm (2.1 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec7676131132149112114101711207653
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Decatur

In Decatur in December, humidity is 87%. With an average temperature of 2°C (36°F), this humidity feels like an unwelcome chill that seeps into your bones, making outdoor exploration feel damp and heavy, and encouraging travelers to seek the warmth of indoor attractions instead.

December Average Humidity in Decatur

This chart illustrates the average monthly humidity levels in Decatur, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Decatur is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%84%83%80%83%82%83%79%79%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Decatur

In Decatur in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Decatur, you can check the information here.

Maximum UV Index Levels in Decatur for December

The chart shows the monthly maximum UV Index (UVI) for Decatur in December, 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 December, the maximum UV index in Decatur typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111198643
Data source: Decatur December 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 December 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 December’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 December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)76 mm (3.0 inches)84%moderate
February Weather0°C (32°F)76 mm (3.0 inches)82%moderate
March Weather6°C (44°F)131 mm (5.2 inches)84%high
April Weather11°C (53°F)132 mm (5.2 inches)83%very high
May Weather19°C (66°F)149 mm (5.9 inches)80%very high
June Weather24°C (75°F)112 mm (4.4 inches)83%extreme
July Weather25°C (78°F)114 mm (4.5 inches)82%extreme
August Weather23°C (74°F)101 mm (4.0 inches)82%very high
September Weather21°C (71°F)71 mm (2.8 inches)79%very high
October Weather14°C (58°F)120 mm (4.7 inches)79%high
November Weather5°C (42°F)76 mm (3.0 inches)88%moderate
December Weather2°C (36°F)53 mm (2.1 inches)87%moderate

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