Afternoon heat in Casselman beats that of 91% of Canadian towns
On a normal January night the air cools to about −11.8°C. October is the wettest month, February the driest. Only about 140 nights a year bring a frost, fewer than in 72% of Canadian towns. If you like long walks, May, June, August and September offer highs of 20–26°C.
ECCC publishes no normals for Casselman itself; the figures are those of Cornwall, 42 km south-east.
A year in Casselman at a glance
Each month’s typical high and low, in °C.
What stands out about Casselman’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in Ontario beside it.
What a year in Casselman feels like
Each season’s and each month’s usual high and low, 1991–2020.
140 frost days and 125 days above 20°C a year
The frost season runs October to April, and January freezes nearly every night. Some 8 nights a year drop under −20°C.
Frost days by month
Average days at 0°C or below
Days above 20°C by month
Average days
Rain and melted snow: about 1,006 mm a year
About 134 days a year bring 1 mm or more.
Rain and snow by month
Millimetres
Rain alone by month
Millimetres
About 198 cm of snow a year
Expect snow from November to April, with about 51 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 Casselman
94% of a year’s heating need falls between October and April. Months averaging under 10°C: October to April.
Behind the figure: the degrees each day’s mean falls under 18°C, summed for the year. Over a year, a home here needs less heating than 71% of Canadian towns.
Living with Casselman’s climate
Gardening, time outside, winter cold and summer heat, from the 1991–2020 normals.
Mild days and mild nights together (17–27°C by day, 8°C or more at night) belong to May, Jun, Aug and Sep.
Parks & trails →Bad-weather days, from blizzards to floods, get their own page for Casselman: the hazards page.
Flood & hazards →ECCC’s normals location: Cornwall
Cornwall is one of the 450 places where ECCC publishes 1991–2020 normals.
| Distance from the town | 42 km south-east |
| Station altitude | 64 m |
| Completeness | meets the WMO “3 and 5” rule |
| WMO standard normals | No |
| Coldest reading, 1991–2020 | −32.0°C |
| Hottest reading, 1991–2020 | 37.5°C |
| Next-nearest location | Angers, 45 km |
How Casselman compares
Against the 2,611 Canadian towns and neighbourhoods of 2,500 or more, each read from its own normals location; the dots are the other locations those towns use in Ontario.
Nearby towns’ climate
Nearby places read from a different ECCC location (places on Casselman’s own would show the same figures).
| Town | July high | January low | Rain & snow |
|---|---|---|---|
| Casselman Cornwall | 27.3°C | −11.8°C | 1,006 mm |
| Limoges 4.3 km · Angers | 26.2°C 1.1°C cooler | −16.5°C 4.7°C colder | 930 mm |
| North Stormont 12 km · Cornwall | 27.3°C about the same | −11.8°C about the same | 1,006 mm |
| Embrun 17 km · Ottawa (Airport) | 27.0°C about the same | −14.3°C 2.5°C colder | 930 mm |
Casselman weather by month
Each month’s normals, 1991–2020: high, low, mean, precipitation and snowfall.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | −3.8°C | −11.8°C | −7.8°C | 80 mm | 51 cm |
| February | −2.1°C | −10.6°C | −6.4°C | 63 mm | 48 cm |
| March | 3.5°C | −5.3°C | −0.9°C | 64 mm | 35 cm |
| April | 11.8°C | 2.0°C | 6.9°C | 83 mm | 11 cm |
| May | 19.8°C | 8.8°C | 14.3°C | 85 mm | 0 cm |
| June | 24.6°C | 14.1°C | 19.3°C | 95 mm | 0 cm |
| July | 27.3°C | 17.0°C | 22.2°C | 97 mm | 0 cm |
| August | 26.3°C | 16.2°C | 21.2°C | 83 mm | 0 cm |
| September | 22.0°C | 11.8°C | 16.9°C | 99 mm | 0 cm |
| October | 14.1°C | 5.7°C | 9.7°C | 100 mm | 1 cm |
| November | 6.9°C | −0.3°C | 3.3°C | 82 mm | 16 cm |
| December | 0.0°C | −6.7°C | −3.3°C | 75 mm | 37 cm |
| Year | 12.5°C | 3.4°C | 8.0°C | 1,006 mm | 198 cm |
The most changeable month: January, give or take 3.0°C; the steadiest, June
Over 1991–2020, March saw both −27.0°C (2003) and 26.0°C (1998), the widest span of any month.
Where Casselman’s numbers come from
Averages over 30 years, not a forecast.
- Normals: ECCC’s normals for Cornwall, 1991–2020, chosen as the nearest location with a full temperature record.
- Comparisons: a pool of Canadian towns and neighbourhoods of 2,500 or more, read alike; whole cities and reserves stay out of it.
- Not on this page: sunshine, not in ECCC’s 1991–2020 normals, and the effect of the town’s height, for which there is no figure.
Canadian Climate Normals 1991–2020 · ECCC Data Services End-use Licence. Data Source: Environment and Climate Change Canada
Questions about Casselman’s climate
How warm does Casselman get in summer?
On a normal day in July the thermometer climbs to 27.3°C, the warmest of the year.
How cold does Casselman get in winter?
Winter bottoms out in January, with lows near −11.8°C.
How much rain and snow does Casselman get?
1,006 mm a year counting snow as water. The wettest month is October (100 mm); the driest, February (63 mm).
Are these figures for Casselman itself?
Only indirectly: the readings are made at Cornwall, outside Casselman.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Casselman →
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).