Ottawa weather by month
Ottawa runs from about -6°C in January to 22°C in July, with August the wettest month at 232 mm.
warmest month
July
22°C
coolest month
January
-6°C
wettest month
August
232 mm
worst air month
February
11 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -6°C | 78 mm | 131 h | 7 |
| February | -4°C | 29 mm | 191 h | 11 |
| March | 2°C | 44 mm | 234 h | 8 |
| April | 7°C | 131 mm | 227 h | 7 |
| May | 15°C | 111 mm | 313 h | 7 |
| June | 19°C | 181 mm | 293 h | 8 |
| July | 22°C | 130 mm | 354 h | 11 |
| August | 20°C | 232 mm | 314 h | 9 |
| September | 18°C | 64 mm | 305 h | 6 |
| October | 10°C | 40 mm | 236 h | 5 |
| November | 5°C | 66 mm | 161 h | 5 |
| December | -5°C | 95 mm | 109 h | 5 |
About 2,868 hours of sun a year. Roughly 120 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.