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December Weather in Charlestown, United States

Last updated: June 24, 2025

In December, the average temperature in Charlestown, United States hovers around 5°C (40°F), with extremes ranging from a chilly -15°C (6°F) to a warm 21°C (71°F). Expect about 104 mm (4.1 in) of precipitation over 10 days, accompanied by a high average humidity of 87%.

December Temperature in Charlestown

In December in Charlestown, the average temperature is 5°C (40°F). Maximum temperatures can reach 21°C (71°F), while minimums can drop as low as -15°C (6°F). Be sure to pack layers and enjoy the diverse weather during your travels!

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

The chart illustrates December temperature patterns in Charlestown, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Charlestown, December typically has an average temperature of 5°C (40°F), with highs reaching up to 21°C (71°F) and lows dropping to around -15°C (6°F).
JanFebMarAprMayJunJulAugSepOctNovDec353947556775787671604540
Data source: Temperature data for Charlestown 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 Charlestown

In Charlestown in December, the precipitation amount is 104 mm (4.1 in) over a period of 10 days.

December Precipitation Trends in Charlestown

The chart displays monthly precipitation patterns in Charlestown, 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 Charlestown, December typically receives around 104 mm (4.1 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec8512013413712814595961059992104
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Charlestown

In Charlestown in December, humidity is 87%. With an average temperature of 5°C (40°F), this humidity feels like a damp chill that wraps around you, making outdoor excursions less enjoyable and requiring extra layers to stay comfortable while exploring.

December Average Humidity in Charlestown

This chart illustrates the average monthly humidity levels in Charlestown, 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 Charlestown is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%86%84%79%82%79%70%69%76%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Charlestown

In Charlestown 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 Charlestown, you can check the information here.

Maximum UV Index Levels in Charlestown for December

The chart shows the monthly maximum UV Index (UVI) for Charlestown 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 Charlestown typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101110108743
Data source: Charlestown 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 Charlestown Compares to Other Months

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

This table compares monthly weather conditions in Charlestown, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (35°F)85 mm (3.3 inches)87%moderate
February Weather4°C (39°F)120 mm (4.7 inches)85%moderate
March Weather8°C (47°F)134 mm (5.3 inches)86%high
April Weather13°C (56°F)137 mm (5.4 inches)84%very high
May Weather19°C (67°F)128 mm (5.1 inches)79%very high
June Weather24°C (75°F)145 mm (5.7 inches)82%extreme
July Weather26°C (78°F)95 mm (3.8 inches)79%very high
August Weather24°C (76°F)96 mm (3.8 inches)70%very high
September Weather22°C (72°F)104 mm (4.1 inches)69%very high
October Weather16°C (60°F)99 mm (3.9 inches)76%high
November Weather7°C (45°F)92 mm (3.6 inches)88%moderate
December Weather5°C (40°F)104 mm (4.1 inches)87%moderate

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