Guelph, Ontario climate data is summarized below. Average annual temperatures range from 2.8 °C (low) to 12.7 °C (high). Annual precipitation averages 856 Millimeters. Guelph is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.63 °C | -2.29 °C | 12 mm |
| February | -11.05 °C | -2.57 °C | 12 mm |
| March | -5.28 °C | 4.5 °C | 46 mm |
| April | 1.26 °C | 12.25 °C | 82 mm |
| May | 7.61 °C | 19.45 °C | 110 mm |
| June | 12.62 °C | 24.02 °C | 111 mm |
| July | 14.91 °C | 26.59 °C | 123 mm |
| August | 14.24 °C | 25.8 °C | 116 mm |
| September | 10.21 °C | 21.59 °C | 83 mm |
| October | 4.99 °C | 14.41 °C | 72 mm |
| November | -0.67 °C | 7.5 °C | 49 mm |
| December | -5.48 °C | 0.67 °C | 40 mm |
| Annual | 2.8 °C | 12.7 °C | 856 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |