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December Weather in Alliston, Canada

Last updated: June 18, 2025

In Alliston, Canada, the average temperature in December hovers around -3°C (28°F), with fluctuations that can see the mercury dipping as low as -29°C (-20°F) and soaring to a maximum of 17°C (63°F). Expect a rainy backdrop with 69 mm (2.7 in) of precipitation spread across 13 days, contributing to a notable average humidity of 91%. Stay warm and dry!

December Temperature in Alliston

In December in Alliston, the average temperature is -3°C (28°F), with maximums reaching up to 17°C (63°F) and minimums dropping as low as -29°C (-20°F). Travelers should prepare for a wide range of temperatures, making layered clothing essential for outdoor activities.

December Weather in Alliston: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Alliston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Alliston, December typically has an average temperature of -3°C (28°F), with highs reaching up to 17°C (63°F) and lows dropping to around -29°C (-20°F).
JanFebMarAprMayJunJulAugSepOctNovDec212331425565706861503627
Data source: Temperature data for Alliston 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 Alliston

In Alliston in December, the precipitation amount is 69 mm (2.7 in) over the course of 13 days.

December Precipitation Trends in Alliston

The chart displays monthly precipitation patterns in Alliston, 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 Alliston, December typically receives around 69 mm (2.7 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec5962591029994909668987669
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Alliston

In Alliston in December humidity is 91%. With an average temperature of -3°C (28°F), this humidity feels like a biting chill that seeps into your bones, making travel uncomfortable and requiring extra layers to brace against the damp cold.

December Average Humidity in Alliston

This chart illustrates the average monthly humidity levels in Alliston, 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 Alliston is approximately 91%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec93%94%87%82%74%68%67%67%74%83%89%91%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Alliston

In Alliston 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 Alliston, you can visit Hourly UV Index in Alliston.

Maximum UV Index Levels in Alliston for December

The chart shows the monthly maximum UV Index (UVI) for Alliston 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 Alliston typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec245899997532
Data source: Alliston 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 Alliston Compares to Other Months

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

This table compares monthly weather conditions in Alliston, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (21°F)59 mm (2.3 inches)93%low
February Weather-5°C (23°F)62 mm (2.5 inches)94%moderate
March Weather-1°C (31°F)58 mm (2.3 inches)87%moderate
April Weather5°C (42°F)102 mm (4.0 inches)82%very high
May Weather13°C (55°F)99 mm (3.9 inches)74%very high
June Weather18°C (65°F)94 mm (3.7 inches)68%very high
July Weather21°C (71°F)90 mm (3.5 inches)67%very high
August Weather20°C (69°F)96 mm (3.8 inches)67%very high
September Weather16°C (61°F)68 mm (2.7 inches)74%high
October Weather10°C (50°F)98 mm (3.9 inches)83%moderate
November Weather2°C (36°F)76 mm (3.0 inches)89%moderate
December Weather-3°C (28°F)69 mm (2.7 inches)91%low

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