South Keys has warmer summer afternoons than 86% of Canadian towns
The coldest hours of a January night bottom out at −14.3°C on average. In January, nights here are colder than in 61% of Canadian towns. Of all months, June brings the most precipitation and February the least. Expect about 154 frosty starts a year, days when the air falls to freezing.
1991–2020 normals from ECCC’s Ottawa (Airport) location, 4.6 km south.
A year in South Keys at a glance
Each month’s typical high and low, in °C.
What stands out about South Keys’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in Ontario beside it.
What a year in South Keys feels like
Typical highs and lows by season and by month, from ECCC’s 1991–2020 normals.
154 frost days and 120 days above 20°C a year
Frost comes from October to April; in January almost every night freezes. Some 16 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 930 mm a year
Some 118 days a year see 1 mm of rain or snow or more.
Rain and snow by month
Millimetres
Rain alone by month
Millimetres
232 cm of snow in a typical year
Expect snow from October to April, with about 59 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 South Keys
93% of a year’s heating need falls between October and April. Months averaging under 10°C: October to April.
Think of it as a year’s worth of daily shortfalls below 18°C, added up.
Living with South Keys’s climate
Gardening, time outside, winter cold and summer heat, from the 1991–2020 normals.
Wait until about 29 April to plant out; frost tends to come back around 7 October, about 160 days later.
For long days outdoors, Jun, Jul, Aug and Sep bring highs of 17–27°C and lows of 8°C or more.
Parks & trails →Winter brings about 47 days with a wind chill below −20.
Humid heat, a humidex over 30, comes on about 49 days a year.
For blizzards, floods and wildfire, turn to South Keys’s hazards page.
Flood & hazards →ECCC’s normals location: Ottawa (Airport)
ECCC builds the Ottawa (Airport) normals from 2 stations’ records over 1991–2020, joined where one replaced another.
| Distance from the town | 4.6 km south |
| Station altitude | 114 m |
| Completeness | at least 25 years |
| WMO standard normals | No |
| Coldest reading, 1991–2020 | −33.1°C |
| Hottest reading, 1991–2020 | 36.9°C |
| Average wind | 13.5 km/h on average, most often from the west |
| Next-nearest location | Ottawa (City), 5.8 km |
How South Keys 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
Nearby places read from a different ECCC location (places on South Keys’s own would show the same figures).
| Town | July high | January low | Rain & snow |
|---|---|---|---|
| South Keys Ottawa (Airport) | 27.0°C | −14.3°C | 930 mm |
| Greenboro West 1.0 km · Ottawa (Airport) | 27.0°C about the same | −14.3°C about the same | 930 mm |
| Ledbury-Heron Gate-Ridgemont 1.7 km · Ottawa (City) | 26.7°C about the same | −14.0°C about the same | 938 mm |
South Keys weather by month
Each month’s normals, 1991–2020: high, low, mean, precipitation and snowfall.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | −5.5°C | −14.3°C | −10.0°C | 70 mm | 59 cm |
| February | −3.6°C | −13.2°C | −8.5°C | 50 mm | 49 cm |
| March | 2.4°C | −7.1°C | −2.4°C | 66 mm | 39 cm |
| April | 11.3°C | 0.5°C | 5.9°C | 81 mm | 12 cm |
| May | 19.6°C | 7.5°C | 13.6°C | 75 mm | under 1 cm |
| June | 24.4°C | 12.9°C | 18.7°C | 97 mm | 0 cm |
| July | 27.0°C | 15.4°C | 21.2°C | 89 mm | 0 cm |
| August | 25.8°C | 14.3°C | 20.1°C | 79 mm | 0 cm |
| September | 21.0°C | 9.6°C | 15.3°C | 90 mm | 0 cm |
| October | 13.0°C | 3.4°C | 8.2°C | 87 mm | 3 cm |
| November | 5.8°C | −2.4°C | 1.7°C | 74 mm | 21 cm |
| December | −1.9°C | −9.6°C | −5.8°C | 72 mm | 50 cm |
| Year | 11.6°C | 1.4°C | 6.5°C | 930 mm | 232 cm |
The most changeable month: January, give or take 3.2°C; the steadiest, August
Bars run from each month’s record low to its record high since 1991. March spans the most, from −29.0°C (2003) to 27.4°C (2012).
Where South Keys’s numbers come from
Averages over 30 years, not a forecast.
- Normals: the closest ECCC location with twelve months of temperature normals, Ottawa (Airport), 1991–2020.
- Comparisons: the 2,500-plus towns and neighbourhoods of Canada, each read from its closest normals location; whole cities and reserves aren’t counted.
- Not on this page: sunshine (no 1991–2020 normals exist for it) and any altitude adjustment, since there is no elevation for the town itself.
Canadian Climate Normals 1991–2020 · ECCC Data Services End-use Licence. Data Source: Environment and Climate Change Canada
Questions about South Keys’s climate
How warm does South Keys get in summer?
At its warmest, in July, the normal high is 27.0°C.
How cold does South Keys get in winter?
The coldest nights come in January, averaging −14.3°C.
How much rain and snow does South Keys get?
Precipitation totals 930 mm a year, with June the wettest month (97 mm) and February the driest (50 mm).
How long does snow stay on the ground?
Around 118 days a year see 1 cm of snow or more lying.
Are these figures for South Keys itself?
They are the normals for Ottawa (Airport), measured just outside South Keys itself.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for South Keys →
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).