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December Weather in Mattoon, United States

Last updated: June 24, 2025

In December, the average temperature in Mattoon, United States hovers around 3°C (37°F), making it a chilly time of year. Temperatures can dip as low as -19°C (-3°F), while reaching highs of 18°C (66°F). Expect about 65 mm (2.6 in) of precipitation spread over 9 days, contributing to an average humidity of a brisk 87%. Prepare for a damp and cool environment!

December Temperature in Mattoon

In December in Mattoon, the average temperature is 3°C (37°F). Maximums can reach 18°C (66°F), while minimums can drop as low as -19°C (-3°F). This weather means travelers should prepare for a mix of chilly days and potentially warmer afternoons, so layering clothing is advisable for an enjoyable visit.

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

The chart illustrates December temperature patterns in Mattoon, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mattoon, December typically has an average temperature of 3°C (37°F), with highs reaching up to 18°C (66°F) and lows dropping to around -19°C (-3°F).
JanFebMarAprMayJunJulAugSepOctNovDec303344536675787471584237
Data source: Temperature data for Mattoon 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 Mattoon

In Mattoon in December, the precipitation amount is 65 mm (2.6 in) over the course of 9 days.

December Precipitation Trends in Mattoon

The chart displays monthly precipitation patterns in Mattoon, 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 Mattoon, December typically receives around 65 mm (2.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec7879125117135110116123671158965
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Mattoon

In Mattoon in December, humidity is 87%. With an average temperature of 3°C (37°F), this humidity feels like a damp chill that clings to your skin, making outdoor activities uncomfortable and necessitating proper layers to stay warm while navigating the wet conditions.

December Average Humidity in Mattoon

This chart illustrates the average monthly humidity levels in Mattoon, 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 Mattoon 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 Mattoon

In Mattoon 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 Mattoon, you can check the information here.

Maximum UV Index Levels in Mattoon for December

The chart shows the monthly maximum UV Index (UVI) for Mattoon 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 Mattoon typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111098643
Data source: Mattoon 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 Mattoon Compares to Other Months

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

This table compares monthly weather conditions in Mattoon, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)78 mm (3.1 inches)84%moderate
February Weather1°C (33°F)79 mm (3.1 inches)82%moderate
March Weather7°C (44°F)125 mm (4.9 inches)84%high
April Weather12°C (53°F)117 mm (4.6 inches)83%very high
May Weather19°C (66°F)135 mm (5.3 inches)80%very high
June Weather24°C (76°F)110 mm (4.3 inches)83%extreme
July Weather25°C (78°F)116 mm (4.6 inches)82%very high
August Weather24°C (75°F)123 mm (4.8 inches)82%very high
September Weather21°C (71°F)67 mm (2.6 inches)79%very high
October Weather14°C (58°F)115 mm (4.5 inches)79%high
November Weather6°C (42°F)89 mm (3.5 inches)88%moderate
December Weather3°C (37°F)65 mm (2.6 inches)87%moderate

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