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December Weather in Mount Vernon, United States

Last updated: June 24, 2025

In Mount Vernon, United States, the average temperature in December hovers around -2°C (28°F). Temperatures can dip as low as -19°C (-2°F), while they can rise to a maximum of 15°C (59°F). Expect 67 mm (2.6 in) of precipitation over 15 days, accompanied by a high average humidity of 87%. Prepare accordingly!

December Temperature in Mount Vernon

In December in Mount Vernon, the average temperature is -2°C (28°F), with maximums reaching 15°C (59°F) and minimums dropping as low as -19°C (-2°F). Travelers should prepare for a wide range of temperatures and pack accordingly for fluctuating weather conditions.

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 -2°C (28°F), with highs reaching up to 15°C (59°F) and lows dropping to around -19°C (-2°F).
JanFebMarAprMayJunJulAugSepOctNovDec272835415058696757443428
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 67 mm (2.6 in) over the course of 15 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 67 mm (2.6 inches) of precipitation spread over approximately 15 days.
JanFebMarAprMayJunJulAugSepOctNovDec701017880734131431566267
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 -2°C (28°F), this humidity feels like a damp chill that seeps into your bones, making outdoor exploration less enjoyable and requiring extra layers to stay warm and comfortable while 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.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%85%83%77%81%77%60%58%75%85%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 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Mount Vernon, you can visit Hourly UV Index in Mount Vernon.

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 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101110108642
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 Weather-3°C (28°F)70 mm (2.7 inches)86%moderate
February Weather-2°C (29°F)101 mm (4.0 inches)86%moderate
March Weather2°C (35°F)78 mm (3.1 inches)85%high
April Weather5°C (41°F)80 mm (3.1 inches)83%very high
May Weather10°C (50°F)73 mm (2.9 inches)77%very high
June Weather15°C (59°F)41 mm (1.6 inches)81%extreme
July Weather20°C (69°F)3 mm (0.1 inches)76%very high
August Weather20°C (68°F)14 mm (0.6 inches)60%very high
September Weather14°C (58°F)31 mm (1.2 inches)58%very high
October Weather6°C (44°F)56 mm (2.2 inches)75%high
November Weather1°C (35°F)62 mm (2.4 inches)85%moderate
December Weather-2°C (28°F)67 mm (2.6 inches)87%low

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