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December Weather in Saint John, United States

Last updated: June 24, 2025

In December, the average temperature in Saint John, United States hovers around 1°C (34°F). Expect chilly extremes, with minimums plunging to -12°C (12°F) and maximums reaching 17°C (64°F). Rain is also a factor, with 70 mm (2.8 in) of precipitation spread over 13 days, contributing to an average humidity level of 86%. Prepare for a damp and crisp month!

December Temperature in Saint John

In December in Saint John, the average temperature is 1°C (34°F), with maximums reaching 17°C (64°F) and minimums dropping as low as -12°C (12°F). Be prepared for a mix of chilly and mild weather, making it essential to pack layers when traveling.

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

The chart illustrates December temperature patterns in Saint John, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Saint John, December typically has an average temperature of 1°C (34°F), with highs reaching up to 17°C (64°F) and lows dropping to around -12°C (12°F).
JanFebMarAprMayJunJulAugSepOctNovDec343442495967767564504134
Data source: Temperature data for Saint John 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 John

In Saint John in December, the precipitation amount is 70 mm (2.8 in) spread over 13 days.

December Precipitation Trends in Saint John

The chart displays monthly precipitation patterns in Saint John, 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 John, December typically receives around 70 mm (2.8 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec62745648452021022547471
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Saint John

In Saint John in December, humidity is 86%. With an average temperature of 1°C (34°F), this humidity feels like a chilling embrace, making outdoor adventures brisk and invigorating but challenging for travel.

December Average Humidity in Saint John

This chart illustrates the average monthly humidity levels in Saint John, 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 John is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%86%86%82%77%79%77%62%60%80%87%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Saint John

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

Maximum UV Index Levels in Saint John for December

The chart shows the monthly maximum UV Index (UVI) for Saint John 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 John typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2456891097532
Data source: Saint John 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 John Compares to Other Months

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

This table compares monthly weather conditions in Saint John, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (35°F)62 mm (2.5 inches)85%low
February Weather1°C (34°F)74 mm (2.9 inches)86%moderate
March Weather6°C (42°F)56 mm (2.2 inches)86%moderate
April Weather10°C (50°F)48 mm (1.9 inches)82%high
May Weather15°C (59°F)45 mm (1.8 inches)77%very high
June Weather20°C (68°F)20 mm (0.8 inches)79%very high
July Weather24°C (76°F)2 mm (0.1 inches)77%very high
August Weather24°C (75°F)10 mm (0.4 inches)62%very high
September Weather18°C (64°F)22 mm (0.9 inches)60%high
October Weather10°C (50°F)54 mm (2.1 inches)80%moderate
November Weather5°C (41°F)74 mm (2.9 inches)87%moderate
December Weather1°C (34°F)70 mm (2.8 inches)86%low

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