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December Weather in Williamsport, United States

Last updated: June 24, 2025

In December, the average temperature in Williamsport, United States hovers around 3°C (38°F). Be prepared for a chilly range, with minimums dipping to -16°C (4°F) and maximums peaking at 19°C (66°F). With 104 mm (4.1 in) of precipitation spread over 11 days, you can expect some wet weather as well. Plus, the average humidity sits at a notable 87%, ensuring a rather damp atmosphere throughout the month.

December Temperature in Williamsport

In December in Williamsport, the average temperature is 3°C (38°F), with a maximum that can reach 19°C (66°F) and a minimum that can drop as low as -16°C (4°F). Travelers should be prepared for a wide range of temperatures, from chilly days to unseasonably warm afternoons.

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

The chart illustrates December temperature patterns in Williamsport, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Williamsport, December typically has an average temperature of 3°C (38°F), with highs reaching up to 19°C (66°F) and lows dropping to around -16°C (4°F).
JanFebMarAprMayJunJulAugSepOctNovDec323644536572777470594338
Data source: Temperature data for Williamsport 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 Williamsport

In Williamsport in December, the precipitation amount is 104 mm (4.1 in) over the course of 11 days.

December Precipitation Trends in Williamsport

The chart displays monthly precipitation patterns in Williamsport, 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 Williamsport, December typically receives around 104 mm (4.1 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec81110123126127130109919110296104
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Williamsport

In Williamsport in December humidity is 87%. With an average temperature of 3°C (38°F), this humidity feels like a chilly blanket wrapped around you, making travel quite uncomfortable as the cold dampness seeps into your clothes and lingers in the air, often leaving you shivering and longing for warmer, drier conditions.

December Average Humidity in Williamsport

This chart illustrates the average monthly humidity levels in Williamsport, 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 Williamsport is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%87%85%81%82%81%73%73%78%89%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Williamsport

In Williamsport 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 Williamsport, you can check the information here.

Maximum UV Index Levels in Williamsport for December

The chart shows the monthly maximum UV Index (UVI) for Williamsport 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 Williamsport typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098643
Data source: Williamsport 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 Williamsport Compares to Other Months

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

This table compares monthly weather conditions in Williamsport, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)81 mm (3.2 inches)88%moderate
February Weather2°C (37°F)109 mm (4.3 inches)88%moderate
March Weather7°C (44°F)123 mm (4.8 inches)87%high
April Weather12°C (53°F)126 mm (5.0 inches)85%very high
May Weather18°C (65°F)127 mm (5.0 inches)81%very high
June Weather22°C (73°F)130 mm (5.1 inches)82%very high
July Weather25°C (77°F)109 mm (4.3 inches)81%very high
August Weather24°C (75°F)91 mm (3.6 inches)73%very high
September Weather21°C (70°F)91 mm (3.6 inches)73%very high
October Weather15°C (59°F)102 mm (4.0 inches)78%high
November Weather6°C (43°F)96 mm (3.8 inches)89%moderate
December Weather3°C (38°F)104 mm (4.1 inches)87%moderate

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