Climate averages 1991–2020
Sarnia weather
in December.
A cold month with moderate precipitation: the 10th warmest and the 2nd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cold month in Sarnia: daytime highs average 1.8°C and nights cool to about -3.3°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 56 mm of precipitation on roughly 9 days, which makes December a month with moderate precipitation (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 9 h 05 min on an average December day.
The nearest other city in this atlas is Clinton Township (61 km away). In December its highs average 2.0°C, about as warm as Sarnia, with 56 mm of rain.
Among the 86 cities listed in Canada, Sarnia ranks joint 27th of 86 for the warmest December highs and joint 14th of 86 for the driest December (precipitation, lowest first). The mean December high of those 86 cities is 0.2°C; Sarnia is 1.6°C warmer than that mean.
From December to January, average highs fall by 3.0°C to -1.2°C, and monthly precipitation rises from 56 mm to 57 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
Sarnia climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.2°C-7.8°C | -7.8°C | 57 | 9.6 | 9.49 h |
| February | -0.3°C-8.0°C | -8.0°C | 52 | 8.4 | 10.510 h |
| March | 4.6°C-3.7°C | -3.7°C | 57 | 9.6 | 11.912 h |
| April | 11.4°C2.8°C | 2.8°C | 85 | 11.4 | 13.413 h |
| May | 18.3°C9.7°C | 9.7°C | 85 | 12.0 | 14.615 h |
| June | 23.7°C15.9°C | 15.9°C | 87 | 10.7 | 15.315 h |
| July | 26.1°C18.8°C | 18.8°C | 71 | 11.0 | 15.015 h |
| August | 25.2°C18.3°C | 18.3°C | 70 | 10.4 | 13.914 h |
| September | 21.7°C14.7°C | 14.7°C | 73 | 9.1 | 12.513 h |
| October | 14.7°C8.5°C | 8.5°C | 76 | 10.8 | 11.111 h |
| November | 7.7°C2.2°C | 2.2°C | 66 | 9.7 | 9.810 h |
| December, selected | 1.8°C-3.3°C | -3.3°C | 56 | 9.4 | 9.19 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
- Clinton Township in DecemberUnited States · 61 kmHigh 2.0°C · Low -3.3°C · 56 mm rain
- Shelby in DecemberUnited States · 62 kmHigh 1.9°C · Low -3.8°C · 55 mm precipitation
- Sterling Heights in DecemberUnited States · 68 kmHigh 2.1°C · Low -3.6°C · 56 mm rain
- Rochester Hills in DecemberUnited States · 70 kmHigh 1.8°C · Low -4.1°C · 56 mm precipitation
- Warren in DecemberUnited States · 74 kmHigh 2.1°C · Low -3.8°C · 56 mm rain
- Troy in DecemberUnited States · 74 kmHigh 1.9°C · Low -3.9°C · 57 mm precipitation
- Southfield in DecemberUnited States · 87 kmHigh 2.1°C · Low -3.8°C · 57 mm rain
- Waterford in DecemberUnited States · 88 kmHigh 1.7°C · Low -4.2°C · 56 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 Sarnia) is explained once on the Sarnia year overview and on the Sources, method and limits page.