Thunder Bay weather in December 2025

Expect -6°C daytime maximum temperatures in the shade with on average 3 hours of sunshine per day in Thunder Bay in December based on long-term weather averages. There is usually 11 days with some rainfall and 45 mm of average monthly rainfall in December.

  • -6°C maximum daytime temperature in December in Thunder Bay-6
    -6°C max day temperature
  • 3 hours of sunshine per day
  • 11 days with some rainfall in December in Thunder Bay11
    11 days with some rainfall
  • -16°C minimum night-time temperature in December in Thunder Bay-16
    -16°C min night temperature
  • 8 hours of daylight per day in December in Thunder Bay8
    8 hours of daylight per day
  • No heat & humidity in December in Thunder Bay0
    No heat & humidity
  • 45 mm monthly rainfall in December in Thunder Bay45
    45 mm of monthly rainfall
  • UV (maximum) index 1 (Low) in December in Thunder Bay1
    1 (Low) UV index
  • 4°C sea temperature in December in Thunder Bay4
    4°C sea temperature

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The December weather guide for Ontario (Thunder Bay) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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More about Ontario

How cold is it in Thunder Bay in December?

Daytime temperatures usually reach -6°C in Thunder Bay in December, falling to -16°C at night.

How sunny is it in Thunder Bay in December?

There are normally 3 hours of bright sunshine each day in Thunder Bay in December - that's 35% of daylight hours.

Is the sea cold around Thunder Bay in December?

The average sea temperature around Thunder Bay in December is 4°C.

Does it rain in Thunder Bay in December?

There are usually 11 days with some rain in Thunder Bay in December and the average monthly rainfall is 45mm. Rain may fall as snow in this month.

Thunder Bay December sunrise & sunset times

Browse the sunrise and sunset times for Thunder Bay in December 2025. Select a month to view Thunder Bay sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st December 2025 08:28 17:04
Tuesday, 16th December 2025 08:43 17:03
Wednesday, 31st December 2025 08:49 17:12

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