nomadseason

December Weather in Ottawa, United States

Last updated: June 24, 2025

In December, the average temperature in Ottawa, United States hovers around 4°C (39°F). Temperature extremes can be quite drastic, with a minimum of -16°C (3°F) and a maximum of 22°C (73°F). Expect 33 mm (1.3 in) of precipitation spread over 4 days, accompanied by a notable average humidity of 84%.

December Temperature in Ottawa

In December in Ottawa, the average temperature is 4°C (39°F), with maximums reaching up to 22°C (73°F) and minimums dropping as low as -16°C (3°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Ottawa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Ottawa, December typically has an average temperature of 4°C (39°F), with highs reaching up to 22°C (73°F) and lows dropping to around -16°C (3°F).
JanFebMarAprMayJunJulAugSepOctNovDec333447556677807772584539
Data source: Temperature data for Ottawa generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Ottawa

In Ottawa in December, the precipitation amount is 33 mm (1.3 in) over a span of 4 days.

December Precipitation Trends in Ottawa

The chart displays monthly precipitation patterns in Ottawa, 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 Ottawa, December typically receives around 33 mm (1.3 inches) of precipitation spread over approximately 4 days.
JanFebMarAprMayJunJulAugSepOctNovDec56369996196109112120811154133
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Ottawa

In Ottawa in December, humidity is 84%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making outdoor excursions uncomfortable and demanding more layers than you anticipate while traveling.

December Average Humidity in Ottawa

This chart illustrates the average monthly humidity levels in Ottawa, 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 Ottawa is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Ottawa

In Ottawa 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 Ottawa, you can check the information here.

Maximum UV Index Levels in Ottawa for December

The chart shows the monthly maximum UV Index (UVI) for Ottawa 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 Ottawa typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3679101111109743
Data source: Ottawa 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 Ottawa Compares to Other Months

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

This table compares monthly weather conditions in Ottawa, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)56 mm (2.2 inches)76%moderate
February Weather1°C (34°F)36 mm (1.4 inches)77%high
March Weather9°C (48°F)98 mm (3.9 inches)70%high
April Weather13°C (55°F)96 mm (3.8 inches)73%very high
May Weather19°C (66°F)196 mm (7.7 inches)82%very high
June Weather25°C (77°F)109 mm (4.3 inches)82%extreme
July Weather27°C (80°F)112 mm (4.4 inches)81%extreme
August Weather25°C (77°F)120 mm (4.7 inches)78%very high
September Weather22°C (73°F)81 mm (3.2 inches)71%very high
October Weather14°C (58°F)115 mm (4.5 inches)71%high
November Weather7°C (45°F)41 mm (1.6 inches)81%moderate
December Weather4°C (39°F)33 mm (1.3 inches)84%moderate

Compare Ottawa's Climate with Cities Worldwide