Chatham, Ontario climate data is summarized below. Average annual temperatures range from 40.9 °F (low) to 57.6 °F (high). Annual precipitation averages 29.6 Inches. 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 | -22 °F | -18.2 °F | 558.8 in. |
| February | -22.5 °F | -18.4 °F | 457.2 in. |
| March | -18.9 °F | -14.1 °F | 1346.2 in. |
| April | -16 °F | -10 °F | 1905 in. |
| May | -12.4 °F | -6.1 °F | 2082.8 in. |
| June | -9.5 °F | -3.3 °F | 2209.8 in. |
| July | -8.3 °F | -2.2 °F | 2387.6 in. |
| August | -8.7 °F | -2.8 °F | 2133.6 in. |
| September | -11.2 °F | -5.2 °F | 1803.4 in. |
| October | -14 °F | -8.8 °F | 1574.8 in. |
| November | -17.1 °F | -12.9 °F | 1549.4 in. |
| December | -19.7 °F | -16.4 °F | 1066.8 in. |
| Annual | 40.9 °F | 57.6 °F | 29.58 in. |
| 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 : -5°F to 0°F |
| Current Drought Conditions | Normal |