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December Weather in Sullivan, United States

Last updated: June 24, 2025

In December, the average temperature in Sullivan, United States hovers around 4°C (40°F). Expect a wide range of temperatures, with a minimum dipping to -15°C (4°F) and a maximum reaching up to 24°C (76°F). The region typically experiences 56 mm (2.2 in) of precipitation over 6 days, and the average humidity sits at a high 86%, making it a rather chilly and damp time of year.

December Temperature in Sullivan

In December in Sullivan, the average temperature is 4°C (40°F). Maximum temperatures can reach 24°C (76°F), while minimums can drop as low as -15°C (4°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Sullivan, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sullivan, December typically has an average temperature of 4°C (40°F), with highs reaching up to 24°C (76°F) and lows dropping to around -15°C (4°F).
JanFebMarAprMayJunJulAugSepOctNovDec333647556675797572594540
Data source: Temperature data for Sullivan 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 Sullivan

In Sullivan in December, the precipitation amount is 56 mm (2.2 in) spread over 6 days.

December Precipitation Trends in Sullivan

The chart displays monthly precipitation patterns in Sullivan, 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 Sullivan, December typically receives around 56 mm (2.2 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec768412813216587100127531076856
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Sullivan

In Sullivan in December humidity is 86%. With an average temperature of 4°C (40°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities uncomfortable and travel cumbersome as you navigate through a thick, heavy air that clings to your skin.

December Average Humidity in Sullivan

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

In Sullivan 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 Sullivan, you can check the information here.

Maximum UV Index Levels in Sullivan for December

The chart shows the monthly maximum UV Index (UVI) for Sullivan 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 Sullivan typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109753
Data source: Sullivan 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 Sullivan Compares to Other Months

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

This table compares monthly weather conditions in Sullivan, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (33°F)76 mm (3.0 inches)82%moderate
February Weather2°C (36°F)84 mm (3.3 inches)80%moderate
March Weather8°C (48°F)128 mm (5.1 inches)80%high
April Weather13°C (55°F)132 mm (5.2 inches)80%very high
May Weather19°C (66°F)165 mm (6.5 inches)82%very high
June Weather24°C (76°F)87 mm (3.4 inches)83%extreme
July Weather26°C (79°F)100 mm (3.9 inches)81%extreme
August Weather24°C (76°F)126 mm (5.0 inches)80%very high
September Weather22°C (72°F)53 mm (2.1 inches)76%very high
October Weather15°C (59°F)107 mm (4.2 inches)76%high
November Weather7°C (45°F)68 mm (2.7 inches)85%moderate
December Weather4°C (40°F)56 mm (2.2 inches)86%moderate

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