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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 3°C (37°F), with extremes ranging from a chilly -14°C (8°F) to a warm 24°C (76°F). Expect about 32 mm (1.3 in) of precipitation spread over 2 days, while the air maintains a notable average humidity of 83%.

December Temperature in Saint John

In December in Saint John, the average temperature is 3°C (37°F). Maximums can reach 24°C (76°F), while minimums can drop as low as -14°C (8°F). Travelers should be prepared for a wide range of temperatures, from mild days to very cold nights.

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 3°C (37°F), with highs reaching up to 24°C (76°F) and lows dropping to around -14°C (8°F).
JanFebMarAprMayJunJulAugSepOctNovDec323346546577817873564537
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 32 mm (1.3 in) over a duration of 2 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 32 mm (1.3 inches) of precipitation spread over approximately 2 days.
JanFebMarAprMayJunJulAugSepOctNovDec2621685016862587462812432
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 83%. With an average temperature of 3°C (37°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and encouraging travelers to seek indoor attractions or cozy cafes.

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 83%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec75%76%67%70%82%82%81%76%67%72%80%83%
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 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 Saint John, you can check the information here.

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 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec4579101111109753
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 Weather0°C (33°F)25 mm (1.0 inches)75%moderate
February Weather1°C (34°F)21 mm (0.8 inches)76%moderate
March Weather8°C (47°F)68 mm (2.7 inches)67%high
April Weather12°C (54°F)50 mm (2.0 inches)70%very high
May Weather18°C (65°F)168 mm (6.6 inches)82%very high
June Weather25°C (77°F)62 mm (2.4 inches)82%extreme
July Weather27°C (81°F)58 mm (2.3 inches)81%extreme
August Weather25°C (78°F)74 mm (2.9 inches)76%very high
September Weather23°C (73°F)62 mm (2.4 inches)67%very high
October Weather14°C (57°F)81 mm (3.2 inches)72%high
November Weather7°C (45°F)24 mm (0.9 inches)80%moderate
December Weather3°C (37°F)32 mm (1.3 inches)83%moderate

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