Frosty mornings in Perth South are scarcer than in 75% of Canadian towns
Midsummer highs settle at about 26.6°C. Its July heat outdoes that of 70% of Canadian towns. Rain and snow are spread evenly through the year: the wettest month, September, gets little more than the driest, February. Plan for rain or snow on about 128 days a year, the days with 1 mm or more.
The nearest ECCC normals location to Perth South is London, 30 km south, and every figure on this page is its.
A year in Perth South at a glance
Each month’s typical high and low, in °C.
What stands out about Perth South’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in Ontario beside it.
What a year in Perth South feels like
Seasons and months as ECCC’s 1991–2020 normals give them: a typical day’s high and low.
About 139 frosts and 128 warm days a year
The frost season runs October to May, and January freezes nearly every night. Some 11 days a year climb past 30°C.
Frost days by month
Average days at 0°C or below
Days above 20°C by month
Average days
About 962 mm of rain and snow a year
Rain and snow by month
Millimetres
About 152 cm of snow a year
From October to April snow is likely; January is the peak, at about 43 cm.
Snowfall by month
Centimetres
Snow on the ground by month
Centimetres at month’s end
London publishes no full year of snowfall, so these figures come from Strathroy-Mullifarry, 58 km away.
Heating a home in Perth South
92% of a year’s heating need falls between October and April. Months averaging under 10°C: October to April.
A day averaging 10 degrees under 18°C adds 10 to the total; warm days add nothing. By this count, homes here need less heating than 79% of Canadian towns.
Living with Perth South’s climate
The averages read for the garden, the outdoors and the coldest and hottest days.
Count on about 165 frost-free days: the last frost averages 3 May, the first 16 October.
Highs of 17–27°C with nights of 8°C or more come in Jun, Jul, Aug and Sep.
Parks & trails →Expect around 18 days a year when the wind chill sinks below −20.
Count on some 55 humid days a year with the humidex past 30.
Bad-weather days, from blizzards to floods, get their own page for Perth South: the hazards page.
Flood & hazards →ECCC’s normals location: London
London is a composite: ECCC joins 3 stations’ readings to make its 1991–2020 normals.
| Distance from the town | 30 km south |
| Station altitude | 278 m |
| Completeness | meets the WMO “3 and 5” rule |
| WMO standard normals | No |
| Snowfall from | Strathroy-Mullifarry, 58 km |
| Coldest reading, 1991–2020 | −29.1°C |
| Hottest reading, 1991–2020 | 37.0°C |
| Average wind | 14.0 km/h on average, most often from the west |
| Next-nearest location | Strathroy-Mullifarry, 58 km |
How Perth South compares
Placed among 2,611 Canadian towns and neighbourhoods of 2,500+, each on its nearest normals location; each dot is another location used in Ontario.
Nearby towns’ climate
Places around Perth South whose figures come from another normals location. No closer places have figures: these lie 28–39 km from Perth South.
| Town | July high | January low | Rain & snow |
|---|---|---|---|
| Perth South London | 26.6°C | −9.1°C | 962 mm |
| Perth East 28 km · Elora | 25.4°C 1.2°C cooler | −10.7°C 1.6°C colder | 851 mm |
| Exeter 32 km · Strathroy-Mullifarry | 27.3°C 0.7°C warmer | −8.5°C 0.6°C milder | 966 mm |
| Woodstock 35 km · Delhi | 27.5°C 0.9°C warmer | −8.9°C about the same | 965 mm |
| New Hamburg 39 km · Kitchener/Waterloo | 26.6°C about the same | −10.3°C 1.2°C colder | 851 mm |
| Seaforth 39 km · Goderich | 24.4°C 2.2°C cooler | −7.8°C 1.3°C milder | 1,035 mm |
Perth South weather by month
Each month’s normals, 1991–2020: high, low, mean, precipitation and snowfall.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | −1.6°C | −9.1°C | −5.4°C | 79 mm | 43 cm |
| February | −0.6°C | −9.0°C | −4.8°C | 63 mm | 32 cm |
| March | 4.6°C | −4.5°C | 0.1°C | 67 mm | 20 cm |
| April | 12.2°C | 1.4°C | 6.8°C | 89 mm | 5 cm |
| May | 19.3°C | 7.7°C | 13.5°C | 89 mm | under 1 cm |
| June | 24.4°C | 13.2°C | 18.8°C | 86 mm | 0 cm |
| July | 26.6°C | 15.3°C | 21.0°C | 81 mm | 0 cm |
| August | 25.7°C | 14.4°C | 20.1°C | 67 mm | 0 cm |
| September | 22.1°C | 10.5°C | 16.3°C | 93 mm | 0 cm |
| October | 14.7°C | 5.0°C | 9.9°C | 83 mm | 2 cm |
| November | 7.5°C | −0.3°C | 3.6°C | 88 mm | 13 cm |
| December | 1.4°C | −5.2°C | −2.0°C | 79 mm | 37 cm |
| Year | 13.0°C | 3.3°C | 8.2°C | 962 mm | 152 cm |
From year to year, February moves by 3.0°C, more than any month, and June least
Over 1991–2020, March saw both −25.6°C (2003) and 27.2°C (2012), the widest span of any month.
Where Perth South’s numbers come from
Averages over 30 years, not a forecast.
- Normals: the closest ECCC location with twelve months of temperature normals, London, 1991–2020.
- Other locations: where a location publishes no full year of precipitation or snowfall, the nearest one that does supplies it, named beside those figures.
- Comparisons: all Canadian places of 2,500 or more except city totals and reserves, each read the same way.
- 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 Perth South’s climate
How warm does Perth South get in summer?
A normal July afternoon tops out at about 26.6°C, the year’s high point.
How cold does Perth South get in winter?
January nights average −9.1°C, the coldest of the year.
How much rain and snow does Perth South get?
The yearly total is about 962 mm. September gets 93 mm, the most of any month; February gets 63 mm, the least.
Are these figures for Perth South itself?
They describe London, the nearest normals location, rather than Perth South itself.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Perth South →
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).