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December Weather in Mount Vernon, United States

Last updated: June 24, 2025

In December, the average temperature in Mount Vernon, United States hovers around 5°C (41°F), with extremes ranging from a chilly -16°C (4°F) to a balmy 22°C (72°F). Expect precipitation of about 88 mm (3.4 in) over the course of 7 days, and prepare for relatively high humidity, averaging at 87%.

December Temperature in Mount Vernon

In December in Mount Vernon, the average temperature is 5°C (41°F). The maximum can reach 22°C (72°F), while the minimum can be as low as -16°C (4°F). Be prepared for a wide range of temperatures, making it essential to pack layers for your trip.

December Weather in Mount Vernon: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Mount Vernon, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Mount Vernon, December typically has an average temperature of 5°C (41°F), with highs reaching up to 22°C (72°F) and lows dropping to around -16°C (4°F).
JanFebMarAprMayJunJulAugSepOctNovDec343748566877807773604540
Data source: Temperature data for Mount Vernon 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 Mount Vernon

In Mount Vernon in December, the precipitation amount is 88 mm (3.4 in) over the course of 7 days.

December Precipitation Trends in Mount Vernon

The chart displays monthly precipitation patterns in Mount Vernon, 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 Mount Vernon, December typically receives around 88 mm (3.4 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec931071431321651009486641219188
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Mount Vernon

In Mount Vernon in December humidity is 87%. With an average temperature of 5°C (41°F), this humidity feels like a heavy, damp blanket enveloping you, making every step seem laborious and the chill more biting, which can be quite challenging for traveling.

December Average Humidity in Mount Vernon

This chart illustrates the average monthly humidity levels in Mount Vernon, 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 Mount Vernon is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%84%83%80%83%82%83%79%79%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Mount Vernon

In Mount Vernon 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 Mount Vernon, you can check the information here.

Maximum UV Index Levels in Mount Vernon for December

The chart shows the monthly maximum UV Index (UVI) for Mount Vernon 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 Mount Vernon typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579111110109753
Data source: Mount Vernon 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 Mount Vernon Compares to Other Months

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

This table compares monthly weather conditions in Mount Vernon, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)93 mm (3.7 inches)84%moderate
February Weather3°C (38°F)107 mm (4.2 inches)82%moderate
March Weather9°C (48°F)143 mm (5.6 inches)84%high
April Weather14°C (57°F)131 mm (5.2 inches)83%very high
May Weather20°C (69°F)165 mm (6.5 inches)80%extreme
June Weather25°C (77°F)100 mm (3.9 inches)83%extreme
July Weather27°C (80°F)94 mm (3.7 inches)82%very high
August Weather25°C (77°F)86 mm (3.4 inches)82%very high
September Weather23°C (73°F)64 mm (2.5 inches)79%very high
October Weather16°C (61°F)121 mm (4.8 inches)79%high
November Weather7°C (45°F)91 mm (3.6 inches)88%moderate
December Weather5°C (41°F)88 mm (3.4 inches)87%moderate

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