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December Weather in Saint Marys, United States

Last updated: June 24, 2025

In December, the average temperature in Saint Marys, United States is a chilly 0°C (32°F), with extremes ranging from a frigid -18°C (0°F) to a mild 16°C (61°F). Expect 98 mm (3.9 in) of precipitation over approximately 13 days, contributing to an average humidity of 88%. Be prepared for a damp and cool atmosphere!

December Temperature in Saint Marys

In December in Saint Marys, the average temperature is 0°C (32°F). The maximum can reach 16°C (61°F), while the minimum can drop as low as -18°C (0°F). Be sure to pack warm clothing if you're planning to visit during this time.

December Weather in Saint Marys: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Saint Marys, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint Marys, December typically has an average temperature of 0°C (32°F), with highs reaching up to 16°C (61°F) and lows dropping to around -18°C (0°F).
JanFebMarAprMayJunJulAugSepOctNovDec252936465765706963523831
Data source: Temperature data for Saint Marys 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 Saint Marys

In Saint Marys in December, the precipitation amount is 98 mm (3.9 in) over a span of 13 days.

December Precipitation Trends in Saint Marys

The chart displays monthly precipitation patterns in Saint Marys, 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 Saint Marys, December typically receives around 98 mm (3.9 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec9010794124144123117941111259498
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Saint Marys

In Saint Marys in December, humidity is 88%. With an average temperature of 0°C (32°F), this humidity feels like a chilly, damp blanket enveloping you, making travel uncomfortable as every breath seems to carry the weight of the cold moisture, turning each step into a struggle against the biting chill.

December Average Humidity in Saint Marys

This chart illustrates the average monthly humidity levels in Saint Marys, 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 Saint Marys is approximately 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%89%88%80%79%74%64%67%81%89%88%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Saint Marys

In Saint Marys 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 Saint Marys, you can visit Hourly UV Index in Saint Marys.

Maximum UV Index Levels in Saint Marys for December

The chart shows the monthly maximum UV Index (UVI) for Saint Marys 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 Saint Marys typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Saint Marys 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 Saint Marys Compares to Other Months

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

This table compares monthly weather conditions in Saint Marys, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (26°F)90 mm (3.5 inches)89%moderate
February Weather-2°C (29°F)107 mm (4.2 inches)90%moderate
March Weather2°C (36°F)94 mm (3.7 inches)89%high
April Weather8°C (46°F)124 mm (4.9 inches)88%very high
May Weather14°C (58°F)144 mm (5.7 inches)80%very high
June Weather19°C (66°F)123 mm (4.9 inches)79%very high
July Weather21°C (71°F)117 mm (4.6 inches)74%very high
August Weather20°C (69°F)94 mm (3.7 inches)64%very high
September Weather17°C (63°F)111 mm (4.4 inches)67%very high
October Weather11°C (53°F)125 mm (4.9 inches)81%high
November Weather3°C (38°F)94 mm (3.7 inches)89%moderate
December Weather0°C (32°F)98 mm (3.9 inches)88%low

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