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December Weather in St. Catharines, Canada

Last updated: June 18, 2025

In December, the average temperature in St. Catharines, Canada hovers around 1°C (35°F). Expect to experience a chilly range, with minimums plunging to -17°C (2°F) and maximums reaching up to 15°C (60°F). Be prepared for some moisture, as precipitation averages 86 mm (3.4 in) over about 13 days, while the air carries a high level of humidity at 87%.

December Temperature in St. Catharines

In December in St. Catharines, the average temperature is 1°C (35°F). The maximum can reach 15°C (60°F) and the minimum can be as low as -17°C (2°F). Travelers should be prepared for a wide range of temperatures and pack accordingly for both warm and cold conditions.

December Weather in St. Catharines: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in St. Catharines, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In St. Catharines, December typically has an average temperature of 1°C (35°F), with highs reaching up to 15°C (60°F) and lows dropping to around -17°C (2°F).
JanFebMarAprMayJunJulAugSepOctNovDec282935435365737266554234
Data source: Temperature data for St. Catharines 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. Catharines

In St. Catharines, in December, the precipitation amount is 86 mm (3.4 in) over the course of 13 days.

December Precipitation Trends in St. Catharines

The chart displays monthly precipitation patterns in St. Catharines, 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. Catharines, December typically receives around 86 mm (3.4 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec7786711191018210680691268686
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in St. Catharines

In St. Catharines in December humidity is 87%. With an average temperature of 1°C (35°F), this humidity feels like a chilling dampness that seeps into your bones, making travel feel particularly uncomfortable as the cold air clings to your skin and makes each step feel heavier.

December Average Humidity in St. Catharines

This chart illustrates the average monthly humidity levels in St. Catharines, 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. Catharines is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%91%88%88%82%80%77%72%76%83%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in St. Catharines

In St. Catharines 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 St. Catharines, you can visit Hourly UV Index in St. Catharines.

Maximum UV Index Levels in St. Catharines for December

The chart shows the monthly maximum UV Index (UVI) for St. Catharines 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. Catharines typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2458910997532
Data source: St. Catharines 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. Catharines Compares to Other Months

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

This table compares monthly weather conditions in St. Catharines, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-2°C (29°F)77 mm (3.0 inches)91%low
February Weather-2°C (29°F)86 mm (3.4 inches)91%moderate
March Weather1°C (35°F)71 mm (2.8 inches)88%moderate
April Weather6°C (43°F)119 mm (4.7 inches)88%very high
May Weather12°C (54°F)101 mm (4.0 inches)82%very high
June Weather18°C (65°F)82 mm (3.2 inches)79%very high
July Weather23°C (73°F)106 mm (4.2 inches)77%very high
August Weather22°C (72°F)80 mm (3.1 inches)72%very high
September Weather19°C (66°F)69 mm (2.7 inches)76%high
October Weather13°C (56°F)126 mm (4.9 inches)83%moderate
November Weather5°C (42°F)86 mm (3.4 inches)88%moderate
December Weather1°C (35°F)86 mm (3.4 inches)87%low

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