Photo: Canmenwalker · CC BY 4.0Summer arrives in force in Bolton, hotter than in 95% of Canadian towns
Deep winter brings January lows near −8.9°C. Winter and summer sit 36°C apart. Frosty nights are scarcer than in 82% of Canadian towns. Comfortable outdoor weather, highs of 19–26°C, belongs to May, June, August and September.
These are not Bolton’s own readings: ECCC keeps no normals there, so the page uses Toronto Pearson (Airport), 24 km south-east.
A year in Bolton at a glance
Each month’s typical high and low, in °C.
What stands out about Bolton’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in Ontario beside it.
What a year in Bolton feels like
Each season’s and each month’s usual high and low, 1991–2020.
About 131 frosts and 125 warm days a year
Frost comes from October to April; in January almost every night freezes. About 17 days a year top 30°C.
Frost days by month
Average days at 0°C or below
Days above 20°C by month
Average days
807 mm of precipitation in a typical year
June is the wettest month and February the driest. About 106 days a year bring 1 mm or more.
Rain and snow by month
Millimetres
Rain alone by month
Millimetres
115 cm of snow in a typical year
Expect snow from November to April, with about 32 cm in January, the snowiest month.
Snowfall by month
Centimetres
Snow on the ground by month
Centimetres at month’s end
Heating a home in Bolton
93% of a year’s heating need falls between October and April. Months averaging under 10°C: November to April.
One degree below 18°C for one day makes one heating degree day; the year’s days are added together. A house here needs less heating than 83% of Canadian towns.
Living with Bolton’s climate
What the normals mean for a garden, a day outside and the depth of winter.
Gardens get from about 27 April to 20 October without frost, around 174 days in all.
Warm afternoons without cold nights, 17–27°C and 8°C or more, mark May, Jun, Aug and Sep.
Parks & trails →Expect around 21 days a year when the wind chill sinks below −20.
Plan shade and water for about 56 days a year above 30 on the humidex.
A typical year is calm by definition; Bolton’s hazards page covers the exceptions.
Flood & hazards →ECCC’s normals location: Toronto Pearson (Airport)
Toronto Pearson (Airport) is a composite: ECCC joins 2 stations’ readings to make its 1991–2020 normals.
| Distance from the town | 24 km south-east |
| Station altitude | 173 m |
| Completeness | at least 25 years |
| WMO standard normals | No |
| Coldest reading, 1991–2020 | −31.0°C |
| Hottest reading, 1991–2020 | 37.9°C |
| Average wind | 15.7 km/h on average, most often from the west |
| Next-nearest location | Toronto Buttonville (Airport), 35 km |
How Bolton compares
Compared with 2,611 towns and neighbourhoods of 2,500 or more across Canada; the dots mark the other normals locations in Ontario.
Nearby towns’ climate
Places around Bolton whose figures come from another normals location. Bolton has few close neighbours with figures, so the list reaches 20–25 km out.
| Town | July high | January low | Rain & snow |
|---|---|---|---|
| Bolton Toronto Pearson (Airport) | 27.4°C | −8.9°C | 807 mm |
| King 20 km · Toronto Buttonville (Airport) | 27.3°C about the same | −10.1°C 1.2°C colder | 862 mm |
| Mono 25 km · Egbert | 26.0°C 1.4°C cooler | −11.3°C 2.4°C colder | 793 mm |
| Erin 25 km · Elora | 25.4°C 2.0°C cooler | −10.7°C 1.8°C colder | 807 mm |
Bolton weather by month
Average daily high and low, mean temperature, rain and snow (as water) and snowfall by month, 1991–2020.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | −1.2°C | −8.9°C | −5.0°C | 62 mm | 32 cm |
| February | −0.3°C | −8.5°C | −4.4°C | 50 mm | 28 cm |
| March | 5.0°C | −3.8°C | 0.6°C | 51 mm | 17 cm |
| April | 12.0°C | 1.9°C | 7.0°C | 77 mm | 5 cm |
| May | 19.2°C | 8.2°C | 13.7°C | 78 mm | under 1 cm |
| June | 24.5°C | 13.9°C | 19.2°C | 81 mm | 0 cm |
| July | 27.4°C | 16.6°C | 22.1°C | 74 mm | 0 cm |
| August | 26.3°C | 15.8°C | 21.1°C | 69 mm | 0 cm |
| September | 22.3°C | 11.6°C | 16.9°C | 69 mm | 0 cm |
| October | 14.6°C | 5.3°C | 10.0°C | 67 mm | under 1 cm |
| November | 7.9°C | 0.2°C | 4.1°C | 72 mm | 9 cm |
| December | 1.9°C | −5.0°C | −1.6°C | 59 mm | 24 cm |
| Year | 13.3°C | 3.9°C | 8.6°C | 807 mm | 115 cm |
From −24.7°C to 26.0°C: March’s coldest and warmest days since 1991
From one year to the next, January’s average typically shifts by 3.0°C around its normal of −5.0°C, the widest of any month, while June’s shifts by 1.3°C.
Where Bolton’s numbers come from
Averages over 30 years, not a forecast.
- Normals: the 1991–2020 normals from ECCC for Toronto Pearson (Airport), its nearest location with complete temperatures.
- Comparisons: Canada’s towns and neighbourhoods of 2,500+ (no city totals, no reserves), each through its own nearest location.
- Not on this page: a sunshine figure (ECCC published none for 1991–2020) and any lapse-rate correction for height, as the town has no elevation here.
Canadian Climate Normals 1991–2020 · ECCC Data Services End-use Licence. Data Source: Environment and Climate Change Canada
Questions about Bolton’s climate
How warm does Bolton get in summer?
On a normal day in July the thermometer climbs to 27.4°C, the warmest of the year.
How cold does Bolton get in winter?
Expect nights around −8.9°C in January; no month is colder.
How much rain and snow does Bolton get?
Around 807 mm a year in all, from 81 mm in June down to 50 mm in February.
How long does snow stay on the ground?
Snow lies on the ground for about 69 days in a normal year.
Are these figures for Bolton itself?
They are the closest available: the normals for Toronto Pearson (Airport), since Bolton has none.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Bolton →
Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).