Chatham, Ontario climate data is summarized below. Average annual temperatures range from 4.9 °C (low) to 14.3 °C (high). Annual precipitation averages 751 Millimeters. Chatham is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.67 °C | -0.83 °C | 22 mm |
| February | -8.55 °C | -1.03 °C | 18 mm |
| March | -2.05 °C | 6.56 °C | 53 mm |
| April | 3.22 °C | 14.08 °C | 75 mm |
| May | 9.68 °C | 21.02 °C | 82 mm |
| June | 14.84 °C | 26.14 °C | 87 mm |
| July | 17.1 °C | 28.02 °C | 94 mm |
| August | 16.27 °C | 26.94 °C | 84 mm |
| September | 11.8 °C | 22.71 °C | 71 mm |
| October | 6.88 °C | 16.11 °C | 62 mm |
| November | 1.16 °C | 8.8 °C | 61 mm |
| December | -3.52 °C | 2.46 °C | 42 mm |
| Annual | 4.9 °C | 14.3 °C | 751 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |