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December Weather in Manassas, United States

Last updated: June 24, 2025

In Manassas, United States, the average temperature in December hovers around 5°C (41°F). Expect a cool climate where temperatures can dip as low as -11°C (13°F) or rise to a warm 20°C (69°F). During this month, anticipate an average precipitation of 90 mm (3.6 in) spread across 9 days, with humidity levels reaching a brisk 85%.

December Temperature in Manassas

In December in Manassas, the average temperature is 5°C (41°F). The maximum can reach 20°C (69°F), and the minimum can be as low as -11°C (13°F). Travelers should prepare for a wide range of temperatures, ensuring they pack layers to stay comfortable throughout the day.

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

The chart illustrates December temperature patterns in Manassas, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Manassas, December typically has an average temperature of 5°C (41°F), with highs reaching up to 20°C (69°F) and lows dropping to around -11°C (13°F).
JanFebMarAprMayJunJulAugSepOctNovDec374147576675817772624741
Data source: Temperature data for Manassas 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 Manassas

In Manassas in December, the precipitation amount is 90 mm (3.6 in) spread over the course of 9 days.

December Precipitation Trends in Manassas

The chart displays monthly precipitation patterns in Manassas, 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 Manassas, December typically receives around 90 mm (3.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec609579103125108109146951088591
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Manassas

In Manassas in December, humidity is 85%. With an average temperature of 5°C (41°F), this humidity feels like a damp chill that seeps into your bones, making outdoor exploration a challenge as the cold air clings to your skin.

December Average Humidity in Manassas

This chart illustrates the average monthly humidity levels in Manassas, 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 Manassas is approximately 85%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%86%84%78%79%70%59%68%80%87%85%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Manassas

In Manassas 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 Manassas, you can check the information here.

Maximum UV Index Levels in Manassas for December

The chart shows the monthly maximum UV Index (UVI) for Manassas 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 Manassas typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098753
Data source: Manassas 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 Manassas Compares to Other Months

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

This table compares monthly weather conditions in Manassas, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather3°C (37°F)60 mm (2.4 inches)86%moderate
February Weather5°C (41°F)95 mm (3.7 inches)86%moderate
March Weather8°C (47°F)79 mm (3.1 inches)86%high
April Weather14°C (57°F)102 mm (4.0 inches)84%very high
May Weather19°C (67°F)125 mm (4.9 inches)78%very high
June Weather24°C (75°F)108 mm (4.3 inches)79%very high
July Weather27°C (81°F)109 mm (4.3 inches)70%very high
August Weather25°C (78°F)146 mm (5.7 inches)59%very high
September Weather22°C (72°F)95 mm (3.7 inches)68%very high
October Weather17°C (62°F)108 mm (4.3 inches)80%high
November Weather8°C (47°F)85 mm (3.3 inches)86%moderate
December Weather5°C (41°F)90 mm (3.6 inches)85%moderate

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