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December Weather in St. Mary's, United States

Last updated: June 24, 2025

In St. Mary's, United States, the average temperature in December hovers around -11°C (13°F), with potential dips to a chilly -30°C (-21°F) and peaks reaching up to 5°C (42°F). Expect 59 mm (2.3 in) of precipitation across approximately 11 days, all while experiencing an impressive average humidity of 98%. Stay warm and prepare for a wintery adventure!

December Temperature in St. Mary's

In December in St. Mary's, the average temperature is -11°C (13°F). Maximums can reach 5°C (42°F), while minimums can plunge as low as -30°C (-21°F). Travelers should be prepared for extremely cold conditions and dress accordingly to ensure comfort and safety during their visit.

December Weather in St. Mary's: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in St. Mary's, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In St. Mary's, December typically has an average temperature of -11°C (13°F), with highs reaching up to 5°C (42°F) and lows dropping to around -30°C (-21°F).
JanFebMarAprMayJunJulAugSepOctNovDec71217304555565446362013
Data source: Temperature data for St. Mary's 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 St. Mary's

In St. Mary's in December, the precipitation amount is 59 mm (2.3 in) over the course of 11 days.

December Precipitation Trends in St. Mary's

The chart displays monthly precipitation patterns in St. Mary's, 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 St. Mary's, December typically receives around 59 mm (2.3 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec316554476455638691785559
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in St. Mary's

In St. Mary's in December, humidity is 98%. With an average temperature of -11°C (13°F), this humidity feels like trudging through a thick, icy fog, making every step outside feel cold and damp while dampening your spirits as you navigate through the frigid air.

December Average Humidity in St. Mary's

This chart illustrates the average monthly humidity levels in St. Mary's, 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 St. Mary's is approximately 98%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec98%96%85%78%80%86%89%91%92%90%93%98%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in St. Mary's

In St. Mary's in December, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in St. Mary's.

Maximum UV Index Levels in St. Mary's for December

The chart shows the monthly maximum UV Index (UVI) for St. Mary's 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 St. Mary's typically reaches 1, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec113456653211
Data source: St. Mary's 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 St. Mary's Compares to Other Months

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

This table compares monthly weather conditions in St. Mary's, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-14°C (7°F)30 mm (1.2 inches)98%low
February Weather-11°C (12°F)65 mm (2.6 inches)96%low
March Weather-8°C (17°F)54 mm (2.1 inches)85%moderate
April Weather-1°C (30°F)47 mm (1.8 inches)78%moderate
May Weather7°C (45°F)63 mm (2.5 inches)80%moderate
June Weather13°C (55°F)55 mm (2.2 inches)86%high
July Weather14°C (57°F)63 mm (2.5 inches)89%high
August Weather12°C (54°F)86 mm (3.4 inches)91%moderate
September Weather8°C (47°F)91 mm (3.6 inches)92%moderate
October Weather2°C (36°F)78 mm (3.1 inches)90%low
November Weather-7°C (20°F)55 mm (2.2 inches)93%low
December Weather-11°C (13°F)59 mm (2.3 inches)98%low

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