Climate averages 1991–2020
Thunder Bay weather
in December.
A freezing month with light precipitation: the 10th warmest and the 4th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a freezing month in Thunder Bay: daytime highs average -4.8°C and nights cool to about -11.3°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 38 mm of precipitation on roughly 7 days, which makes December a month with light precipitation (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 8 h 24 min on an average December day.
The nearest other city in this atlas is Duluth (278 km away). In December its highs average -3.2°C, 1.7°C warmer than Thunder Bay, with 45 mm of precipitation.
Among the 86 cities listed in Canada, Thunder Bay ranks 78th of 86 for the warmest December highs and 11th of 86 for the driest December (precipitation, lowest first). The mean December high of those 86 cities is 0.2°C; Thunder Bay is 5.0°C cooler than that mean.
From December to January, average highs fall by 4.8°C to -9.6°C, and monthly precipitation falls from 38 mm to 29 mm.
The annual picture
December in context
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Thunder Bay climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -9.6°C-16.6°C | -16.6°C | 29 | 6.5 | 8.89 h |
| February | -8.0°C-15.0°C | -15.0°C | 22 | 4.9 | 10.210 h |
| March | -1.7°C-8.7°C | -8.7°C | 31 | 6.8 | 11.912 h |
| April | 5.1°C-2.2°C | -2.2°C | 54 | 8.3 | 13.614 h |
| May | 12.5°C4.2°C | 4.2°C | 66 | 10.1 | 15.215 h |
| June | 18.3°C10.7°C | 10.7°C | 65 | 10.5 | 16.016 h |
| July | 22.3°C15.3°C | 15.3°C | 76 | 10.6 | 15.716 h |
| August | 22.3°C15.6°C | 15.6°C | 67 | 9.1 | 14.314 h |
| September | 17.8°C11.7°C | 11.7°C | 84 | 10.5 | 12.613 h |
| October | 9.9°C4.8°C | 4.8°C | 72 | 10.4 | 10.911 h |
| November | 2.3°C-2.8°C | -2.8°C | 49 | 7.8 | 9.39 h |
| December, selected | -4.8°C-11.3°C | -11.3°C | 38 | 7.4 | 8.48 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Duluth in DecemberUnited States · 278 kmHigh -3.2°C · Low -8.8°C · 45 mm precipitation
- Sault Ste. Marie in DecemberCanada · 424 kmHigh -1.7°C · Low -7.7°C · 56 mm precipitation
- Green Bay in DecemberUnited States · 440 kmHigh -0.6°C · Low -7.2°C · 45 mm precipitation
- Appleton in DecemberUnited States · 463 kmHigh -1.1°C · Low -7.7°C · 45 mm precipitation
- Brooklyn Park in DecemberUnited States · 481 kmHigh -2.5°C · Low -9.8°C · 35 mm precipitation
- Saint Paul in DecemberUnited States · 482 kmHigh -2.2°C · Low -9.6°C · 35 mm precipitation
- Minneapolis in DecemberUnited States · 487 kmHigh -2.5°C · Low -9.7°C · 35 mm precipitation
- Plymouth, United States in DecemberUnited States · 493 kmHigh -2.5°C · Low -9.6°C · 34 mm precipitation
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Thunder Bay) is explained once on the Thunder Bay year overview and on the Sources, method and limits page.