Guelph weather by month
Guelph runs from about -3°C in January to 21°C in July, with April the wettest month at 131 mm.
warmest month
July
21°C
coolest month
January
-3°C
wettest month
April
131 mm
worst air month
August
12 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -3°C | 111 mm | 85 h | 6 |
| February | -1°C | 18 mm | 210 h | 10 |
| March | 3°C | 67 mm | 199 h | 11 |
| April | 8°C | 131 mm | 243 h | 8 |
| May | 15°C | 93 mm | 348 h | 6 |
| June | 19°C | 111 mm | 317 h | 6 |
| July | 21°C | 124 mm | 391 h | 10 |
| August | 20°C | 100 mm | 321 h | 12 |
| September | 18°C | 75 mm | 314 h | 10 |
| October | 11°C | 42 mm | 261 h | 5 |
| November | 5°C | 48 mm | 123 h | 5 |
| December | -2°C | 87 mm | 94 h | 6 |
About 2,906 hours of sun a year. Roughly 101 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 2026-05-27. Full method, licences and the list of sources we rejected are on the methodology page.