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December Weather in Bethalto, United States

Last updated: June 24, 2025

In December, the average temperature in Bethalto, United States hovers around 3°C (38°F). This season can bring significant extremes, with potential lows plunging to -20°C (-4°F) and highs reaching up to 20°C (69°F). Prepare for a wet month as well, with an average precipitation of 57 mm (2.2 in) spread over 7 days. Additionally, expect a high average humidity of 86%, making it a uniquely chilly and damp time of year.

December Temperature in Bethalto

In December in Bethalto, the average temperature is 3°C (38°F). Maximum can reach 20°C (69°F) and minimum can be as low as -20°C (-4°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Bethalto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Bethalto, December typically has an average temperature of 3°C (38°F), with highs reaching up to 20°C (69°F) and lows dropping to around -20°C (-4°F).
JanFebMarAprMayJunJulAugSepOctNovDec313446546776797672594338
Data source: Temperature data for Bethalto 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 Bethalto

In Bethalto in December, the precipitation amount is 57 mm (2.2 in) over the course of 7 days.

December Precipitation Trends in Bethalto

The chart displays monthly precipitation patterns in Bethalto, 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 Bethalto, December typically receives around 57 mm (2.2 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec7580133132156111100120641037557
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Bethalto

In Bethalto in December humidity is 86%. With an average temperature of 3°C (38°F), this humidity feels like a damp chill that seeps through your layers, making traveling uncomfortable as breath clouds visibly in the crisp air.

December Average Humidity in Bethalto

This chart illustrates the average monthly humidity levels in Bethalto, 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 Bethalto is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Bethalto

In Bethalto 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 Bethalto, you can check the information here.

Maximum UV Index Levels in Bethalto for December

The chart shows the monthly maximum UV Index (UVI) for Bethalto 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 Bethalto typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910111199643
Data source: Bethalto 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 Bethalto Compares to Other Months

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

This table compares monthly weather conditions in Bethalto, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (32°F)75 mm (3.0 inches)82%moderate
February Weather1°C (35°F)80 mm (3.1 inches)80%moderate
March Weather8°C (46°F)133 mm (5.2 inches)80%high
April Weather12°C (55°F)132 mm (5.2 inches)80%very high
May Weather19°C (67°F)156 mm (6.1 inches)82%very high
June Weather25°C (77°F)111 mm (4.4 inches)83%extreme
July Weather26°C (79°F)100 mm (3.9 inches)81%extreme
August Weather24°C (76°F)120 mm (4.7 inches)80%very high
September Weather22°C (72°F)64 mm (2.5 inches)76%very high
October Weather15°C (59°F)102 mm (4.0 inches)76%high
November Weather6°C (44°F)75 mm (2.9 inches)85%moderate
December Weather3°C (38°F)57 mm (2.2 inches)86%moderate

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