Last updated: June 24, 2025
In December, the average temperature in Ontario, United States hovers around 1°C (35°F). Expect a range of -10°C (15°F) to 15°C (60°F), making it a month of contrasts. With 29 mm (1.1 in) of precipitation spread across approximately 8 days, you might want to keep an umbrella handy. Don't forget the high humidity level of 87%, which adds to the chill in the air!
Visiting Ontario in December can be quite a chilly experience, so be sure to dress warmly and enjoy the crisp air!
In Ontario in December, the precipitation amount is 29 mm (1.1 in) over the course of 8 days.
In Ontario 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.
In Ontario 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 Ontario, you can visit Hourly UV Index in Ontario.
UV Risk Categories
Weather in Ontario varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Ontario, focusing on differences in temperature, rainfall, humidity, and UV levels.
Temperature | Precipitation | Humidity | UV | |
---|---|---|---|---|
January Weather | 0°C (33°F) | 42 mm (1.7 inches) | 88% | moderate |
February Weather | 2°C (36°F) | 46 mm (1.8 inches) | 89% | moderate |
March Weather | 8°C (47°F) | 32 mm (1.3 inches) | 85% | high |
April Weather | 12°C (55°F) | 23 mm (0.9 inches) | 79% | high |
May Weather | 17°C (64°F) | 28 mm (1.1 inches) | 71% | very high |
June Weather | 23°C (73°F) | 16 mm (0.6 inches) | 71% | extreme |
July Weather | 29°C (84°F) | 1 mm (0.0 inches) | 66% | very high |
August Weather | 27°C (82°F) | 5 mm (0.2 inches) | 50% | very high |
September Weather | 21°C (70°F) | 10 mm (0.4 inches) | 48% | very high |
October Weather | 12°C (55°F) | 16 mm (0.6 inches) | 65% | moderate |
November Weather | 6°C (43°F) | 27 mm (1.1 inches) | 84% | moderate |
December Weather | 1°C (35°F) | 29 mm (1.1 inches) | 87% | low |