Chesley, Ontario climate data is summarized below. Average annual temperatures range from 2.4 °C (low) to 11.9 °C (high). Annual precipitation averages 692 Millimeters. Chesley 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.02 °C | -2.84 °C | 0 mm |
| February | -11.62 °C | -3.35 °C | 0 mm |
| March | -6.05 °C | 3.39 °C | 32 mm |
| April | 0.71 °C | 11.56 °C | 67 mm |
| May | 6.76 °C | 18.8 °C | 91 mm |
| June | 11.84 °C | 23.52 °C | 96 mm |
| July | 14.13 °C | 25.57 °C | 69 mm |
| August | 13.86 °C | 24.88 °C | 83 mm |
| September | 9.82 °C | 20.63 °C | 89 mm |
| October | 5.24 °C | 13.77 °C | 102 mm |
| November | -0.33 °C | 7.03 °C | 56 mm |
| December | -5.98 °C | 0.15 °C | 7 mm |
| Annual | 2.4 °C | 11.9 °C | 692 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |