Climate averages 1991–2020
Thornhill weather
in December.
A cold month with moderate 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 cold month in Thornhill: daytime highs average 1.7°C and nights cool to about -4.0°C. By daytime temperature it is the 10th warmest of the 12 months.
Expect about 61 mm of precipitation on roughly 10 days, which makes December a month with moderate precipitation (the 4th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 8 h 59 min on an average December day.
The nearest other city in this atlas is Richmond Hill (6 km away). In December its highs average 1.1°C, 0.6°C cooler than Thornhill, with 61 mm of precipitation.
Among the 86 cities listed in Canada, Thornhill ranks joint 32nd of 86 for the warmest December highs and joint 19th of 86 for the driest December (precipitation, lowest first). The mean December high of those 86 cities is 0.2°C; Thornhill is 1.5°C warmer than that mean.
From December to January, average highs fall by 3.1°C to -1.4°C, and monthly precipitation falls from 61 mm to 60 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
Thornhill climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.4°C-8.6°C | -8.6°C | 60 | 10.2 | 9.39 h |
| February | -0.8°C-9.2°C | -9.2°C | 49 | 7.9 | 10.410 h |
| March | 3.8°C-4.6°C | -4.6°C | 57 | 9.5 | 11.912 h |
| April | 10.2°C1.8°C | 1.8°C | 77 | 10.7 | 13.413 h |
| May | 16.9°C8.2°C | 8.2°C | 72 | 10.1 | 14.715 h |
| June | 22.4°C14.2°C | 14.2°C | 77 | 10.6 | 15.415 h |
| July | 25.5°C17.5°C | 17.5°C | 71 | 9.6 | 15.115 h |
| August | 24.8°C17.2°C | 17.2°C | 65 | 8.8 | 14.014 h |
| September | 21.0°C13.7°C | 13.7°C | 69 | 8.7 | 12.613 h |
| October | 14.0°C7.5°C | 7.5°C | 75 | 10.5 | 11.111 h |
| November | 7.1°C1.4°C | 1.4°C | 67 | 10.0 | 9.710 h |
| December, selected | 1.7°C-4.0°C | -4.0°C | 61 | 10.0 | 9.09 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
- Richmond Hill in DecemberCanada · 6 kmHigh 1.1°C · Low -5.3°C · 61 mm precipitation
- Vaughan in DecemberCanada · 6 kmHigh 1.3°C · Low -4.8°C · 61 mm precipitation
- Toronto in DecemberCanada · 12 kmHigh 1.9°C · Low -3.4°C · 61 mm precipitation
- Markham in DecemberCanada · 14 kmHigh 1.5°C · Low -4.8°C · 81 mm precipitation
- Etobicoke in DecemberCanada · 22 kmHigh 2.0°C · Low -3.4°C · 61 mm rain
- Pickering in DecemberCanada · 25 kmHigh 1.0°C · Low -4.9°C · 62 mm precipitation
- Newmarket in DecemberCanada · 26 kmHigh 0.5°C · Low -6.4°C · 57 mm precipitation
- Brampton in DecemberCanada · 31 kmHigh 1.2°C · Low -5.2°C · 59 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 Thornhill) is explained once on the Thornhill year overview and on the Sources, method and limits page.
Toronto, Etobicoke and Vaughan lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.