Bolton climate — normals and trends
Bolton (Canada) has a warm-summer humid continental climate (Dfb) under the Köppen-Geiger classification. Its mean annual temperature is 7.0 °C and it receives 835 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 (20.3 °C on average) and the coldest is January (-6.9 °C). Rainfall peaks in June.
Bolton averages 149 frost days, 10 hot days (≥ 30 °C) and 126 rainy days per year.
Bolton 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 157 to 141 per year over the period.
The hottest day of the period reached 36.8 °C (on 1 July 1963) and the coldest -34.2 °C (on 22 January 2014).
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
BoltonOntario
- coords
- 43.88°, -79.74°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
7.0°C
Average daily high
11.9°C
Average daily low
2.2°C
Annual rainfall
835mm
Sunshine / day
8.7h
Mean relative humidity
73%
Average peak wind
17.6km/h
Seasonal range
27.2°C
Frost days (< 0 °C)
149 d/yr
Hot days (≥ 30 °C)
10 d/yr
Rainy days (≥ 1 mm)
126 d/yr
Annual snowfall
115.6 cm
Average feels-like high
9.4 °C
Average feels-like low
-1.2 °C
Average peak gust
40.5 km/h
Tropical nights (≥ 20 °C)
5 d/yr
Solar radiation
14.0 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.5 °C
since 1940
+0.2 °C per decade · r² = 0.28 · 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
36.8 °C
1 July 1963
Coldest day
-34.2 °C
22 January 2014
Wettest day
101 mm
15 October 1954
Windiest day
49.2 km/h
6 April 1979
Strongest gust
113.8 km/h
6 April 1985
Hottest feels-like
40.0 °C
9 July 1955
Coldest feels-like
-39.2 °C
22 January 2014
Snowiest day
28.1 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 | -3.9 °C | -1.0 °C | 35 mm | -18 mm |
| Feb | -3.0 °C | -1.3 °C | 75 mm | +27 mm |
| Mar | 6.6 °C | +2.9 °C | 65 mm | +4 mm |
| Apr | 11.6 °C | +0.3 °C | 56 mm | -16 mm |
| May | 17.1 °C | -1.0 °C | 91 mm | +10 mm |
| Jun | 24.8 °C | +1.5 °C | 98 mm | +14 mm |
| Jul | 27.8 °C | +1.9 °C | 57 mm | -26 mm |
| Aug | 25.0 °C | +0.3 °C | 54 mm | -26 mm |
| Sep | 22.5 °C | +2.0 °C | 56 mm | -17 mm |
| Oct | 15.3 °C | +1.7 °C | 61 mm | -9 mm |
| Nov | 5.5 °C | -0.7 °C | 52 mm | -16 mm |
| Dec | -1.1 °C | -0.9 °C | 79 mm | +18 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 Bolton?
Bolton has a warm-summer humid continental climate (Köppen Dfb). Over 1940-2025, the average annual temperature is 7.0 °C and it receives 835 mm of precipitation per year.
What is the hottest day ever recorded in Bolton?
The hottest day measured in Bolton between 1940 and 2025 was 1 July 1963, reaching 36.8 °C.
What is the coldest day in Bolton?
The coldest day measured in Bolton between 1940 and 2025 was 22 January 2014, at -34.2 °C.
Does it snow in Bolton?
Yes. Bolton gets on average 115.6 cm of snow per year and has around 149 frost days.
Has the climate of Bolton warmed?
Yes: Bolton warmed by +1.5 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Bolton?
The wettest day measured in Bolton between 1940 and 2025 was 15 October 1954, with 101 mm of rain in 24 hours.
What was the windiest day in Bolton?
The windiest day measured in Bolton between 1940 and 2025 was 6 April 1979, with winds reaching 49.2 km/h.
What is the warmest month in Bolton?
The warmest month in Bolton is July (20.3 °C on average); the coldest is January (-6.9 °C).
How much does it rain in Bolton?
Bolton receives on average 835 mm of precipitation per year, spread over about 126 rainy days.
Is it sunny in Bolton?
Bolton gets on average 8.7 hours of sunshine per day, roughly 3,175 hours per year over 1940-2025.
What is the biggest single-day snowfall in Bolton?
The heaviest 24-hour snowfall measured in Bolton between 1940 and 2025 was 25 February 1965, with 28.1 cm.
Are there tropical nights in Bolton?
Yes: Bolton has on average 5 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Bolton?
In Bolton, between 1940 and 2025, the highest apparent temperature reached 40.0 °C on 9 July 1955, and the lowest was -39.2 °C on 22 January 2014.
Compare Bolton with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Bolton