Summer arrives in force in Old Ottawa South, hotter than in 78% of Canadian towns
Nights in January average −14.0°C. By precipitation alone, it ranks wetter than 60% of Canadian towns. Seasons differ by 41°C, from the coldest nights to the warmest afternoons. Frost comes on about 147 days a year, so leave time to clear the car.
Figures: ECCC’s 1991–2020 normals for Ottawa (City) (3.2 km south-west).
A year in Old Ottawa South at a glance
Each month’s typical high and low, in °C.
What stands out about Old Ottawa South’s climate
Compared with Canadian towns, with its place among towns of 2,500+ in Ontario beside it.
What a year in Old Ottawa South feels like
Each season’s and each month’s usual high and low, 1991–2020.
About 147 frosts and 121 warm days a year
The frost season runs October to April, and January freezes nearly every night. On about 15 nights a year the air falls below −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 938 mm a year
June is the wettest month and February the driest. On about 120 days a year, 1 mm or more falls.
Rain and snow by month
Millimetres
Rain alone by month
Millimetres
Snowfall: about 185 cm in a normal year
From October to April snow is likely; January is the peak, at about 45 cm.
Snowfall by month
Centimetres
Snow on the ground by month
Centimetres at month’s end
Heating a home in Old Ottawa South
93% 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.
Living with Old Ottawa South’s climate
Gardening, time outside, winter cold and summer heat, from the 1991–2020 normals.
A normal year gives the garden about 158 frost-free days, roughly 30 April to 6 October.
Highs of 17–27°C with nights of 8°C or more come in May, Jun, Jul, Aug and Sep.
Parks & trails →Roughly 39 days a year feel colder than −20 in the wind.
About 50 days a year turn sultry, with the humidex past 30.
What averages leave out, the floods and ice storms, is on Old Ottawa South’s hazards page.
Flood & hazards →ECCC’s normals location: Ottawa (City)
Behind the 1991–2020 normals for Ottawa (City) are 2 stations, which ECCC combines into one record.
| Distance from the town | 3.2 km south-west |
| Station altitude | 79 m |
| Completeness | meets the WMO “3 and 5” rule |
| WMO standard normals | Yes |
| Coldest reading, 1991–2020 | −32.2°C |
| Hottest reading, 1991–2020 | 37.3°C |
| Average wind | 11.5 km/h on average, most often from the west |
| Next-nearest location | Ottawa (Airport), 8.0 km |
How Old Ottawa South 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
Nearby places read from a different ECCC location (places on Old Ottawa South’s own would show the same figures). Distances here run 19–27 km: that is how far the nearest places with figures are from Old Ottawa South.
Old Ottawa South weather by month
Each month’s normals, 1991–2020: high, low, mean, precipitation and snowfall.
| Month | High | Low | Mean | Rain & snow | Snow |
|---|---|---|---|---|---|
| January | −5.2°C | −14.0°C | −9.6°C | 65 mm | 45 cm |
| February | −3.3°C | −12.9°C | −8.1°C | 52 mm | 41 cm |
| March | 2.5°C | −6.9°C | −2.2°C | 62 mm | 31 cm |
| April | 11.2°C | 1.1°C | 6.2°C | 81 mm | 8 cm |
| May | 19.4°C | 8.0°C | 13.8°C | 80 mm | 0 cm |
| June | 24.2°C | 13.3°C | 18.8°C | 95 mm | 0 cm |
| July | 26.7°C | 15.8°C | 21.3°C | 92 mm | 0 cm |
| August | 25.6°C | 14.6°C | 20.1°C | 87 mm | 0 cm |
| September | 21.1°C | 10.1°C | 15.6°C | 87 mm | 0 cm |
| October | 13.3°C | 4.1°C | 8.8°C | 90 mm | 2 cm |
| November | 5.8°C | −1.8°C | 2.0°C | 72 mm | 16 cm |
| December | −1.5°C | −8.7°C | −5.1°C | 74 mm | 43 cm |
| Year | 11.7°C | 1.9°C | 6.8°C | 938 mm | 185 cm |
The most changeable month: January, give or take 3.1°C; the steadiest, June
Records from 1991 to 2020: no month spans more than March, between −28.5°C (2003) and 26.5°C (2012).
Where Old Ottawa South’s numbers come from
Averages over 30 years, not a forecast.
- Normals: the 1991–2020 Canadian Climate Normals at Ottawa (City), the closest ECCC location with twelve months of temperature normals.
- Comparisons: every Canadian town and neighbourhood of 2,500 or more, each read from its own nearest location; city totals and reserves are left out.
- 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 Old Ottawa South’s climate
How warm does Old Ottawa South get in summer?
Highs reach 26.7°C on an average July day; no month is warmer.
How cold does Old Ottawa South get in winter?
Of all twelve months, January has the coldest nights, about −14.0°C.
How much rain and snow does Old Ottawa South get?
June is the wettest month at 95 mm and February the driest at 52 mm, for 938 mm over the year.
How long does snow stay on the ground?
A layer of at least 1 cm stays down on about 115 days a year.
Are these figures for Old Ottawa South itself?
Close to it: they are ECCC’s 1991–2020 normals for Ottawa (City), just outside Old Ottawa South’s boundary.
Data Source: Environment and Climate Change Canada · ECCC Data Services End-use Licence Today’s forecast for Old Ottawa 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).