St. Thomas climate — normals and trends
St. Thomas (Canada) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 8.7 °C and it receives 999 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (22.0 °C on average) and the coldest is January (-4.7 °C). Rainfall peaks in June.
St. Thomas averages 115 frost days, 2 hot days (≥ 30 °C) and 135 rainy days per year.
St. Thomas has warmed by +1.5 °C between 1940 and 2025, or +0.18 °C per decade. This trend is statistically significant.
The number of frost days there went from about 129 to 101 per year over the period.
The hottest day of the period reached 34.8 °C (on 9 July 1988) and the coldest -27.9 °C (on 16 February 2015).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
St. ThomasOntario
- coords
- 42.77°, -81.18°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
8.7°C
Average daily high
11.9°C
Average daily low
5.4°C
Annual rainfall
999mm
Sunshine / day
8.9h
Mean relative humidity
74%
Average peak wind
23.4km/h
Seasonal range
26.7°C
Frost days (< 0 °C)
115 d/yr
Hot days (≥ 30 °C)
2 d/yr
Rainy days (≥ 1 mm)
135 d/yr
Annual snowfall
93.3 cm
Average feels-like high
9.4 °C
Average feels-like low
1.9 °C
Average peak gust
40.9 km/h
Tropical nights (≥ 20 °C)
26 d/yr
Solar radiation
14.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.5 °C
since 1940
+0.2 °C per decade · r² = 0.27 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
34.8 °C
9 July 1988
Coldest day
-27.9 °C
16 February 2015
Wettest day
80 mm
25 June 1968
Windiest day
66.7 km/h
26 January 1978
Strongest gust
112.3 km/h
14 January 1940
Hottest feels-like
39.0 °C
17 June 1994
Coldest feels-like
-33.9 °C
17 January 1982
Snowiest day
22.3 cm
25 February 1965
Sunniest day
15.0 h
14 June 1940
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | -2.6 °C | -0.9 °C | 47 mm | -23 mm |
| Feb | -1.5 °C | -0.2 °C | 63 mm | +3 mm |
| Mar | 6.8 °C | +3.6 °C | 100 mm | +20 mm |
| Apr | 10.3 °C | +0.9 °C | 84 mm | -8 mm |
| May | 15.3 °C | -1.5 °C | 93 mm | +3 mm |
| Jun | 22.9 °C | -0.1 °C | 63 mm | -36 mm |
| Jul | 26.1 °C | +0.7 °C | 83 mm | -13 mm |
| Aug | 24.0 °C | -0.5 °C | 46 mm | -42 mm |
| Sep | 22.3 °C | +1.7 °C | 48 mm | -35 mm |
| Oct | 15.8 °C | +1.7 °C | 70 mm | -8 mm |
| Nov | 7.4 °C | +0.1 °C | 61 mm | -24 mm |
| Dec | 0.9 °C | -0.6 °C | 108 mm | +30 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of St. Thomas?
St. Thomas has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 8.7 °C and it receives 999 mm of precipitation per year.
What is the hottest day ever recorded in St. Thomas?
The hottest day measured in St. Thomas between 1940 and 2025 was 9 July 1988, reaching 34.8 °C.
What is the coldest day in St. Thomas?
The coldest day measured in St. Thomas between 1940 and 2025 was 16 February 2015, at -27.9 °C.
Does it snow in St. Thomas?
Yes. St. Thomas gets on average 93.3 cm of snow per year and has around 115 frost days.
Has the climate of St. Thomas warmed?
Yes: St. Thomas warmed by +1.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in St. Thomas?
The wettest day measured in St. Thomas between 1940 and 2025 was 25 June 1968, with 80 mm of rain in 24 hours.
What was the windiest day in St. Thomas?
The windiest day measured in St. Thomas between 1940 and 2025 was 26 January 1978, with winds reaching 66.7 km/h.
What is the warmest month in St. Thomas?
The warmest month in St. Thomas is July (22.0 °C on average); the coldest is January (-4.7 °C).
How much does it rain in St. Thomas?
St. Thomas receives on average 999 mm of precipitation per year, spread over about 135 rainy days.
Is it sunny in St. Thomas?
St. Thomas gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.
What is the biggest single-day snowfall in St. Thomas?
The heaviest 24-hour snowfall measured in St. Thomas between 1940 and 2025 was 25 February 1965, with 22.3 cm.
Are there tropical nights in St. Thomas?
Yes: St. Thomas has on average 26 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in St. Thomas?
In St. Thomas, between 1940 and 2025, the highest apparent temperature reached 39.0 °C on 17 June 1994, and the lowest was -33.9 °C on 17 January 1982.
Compare St. Thomas with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around St. Thomas