Hamilton, Ontario climate data is summarized below. Average annual temperatures range from 40.6 °F (low) to 57.1 °F (high). Annual precipitation averages 38.9 Inches. Hamilton is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -21.8 °F | -17.9 °F | 838.2 in. |
| February | -22.6 °F | -18.2 °F | 914.4 in. |
| March | -19.4 °F | -14.5 °F | 2260.6 in. |
| April | -16.3 °F | -10.7 °F | 2590.8 in. |
| May | -13 °F | -6.7 °F | 2616.2 in. |
| June | -9.9 °F | -3.8 °F | 2692.4 in. |
| July | -8.3 °F | -2.2 °F | 2819.4 in. |
| August | -8.6 °F | -2.8 °F | 2540 in. |
| September | -10.9 °F | -5.3 °F | 1930.4 in. |
| October | -14 °F | -9.2 °F | 2184.4 in. |
| November | -17.1 °F | -12.9 °F | 1778 in. |
| December | -19.7 °F | -16.3 °F | 1905 in. |
| Annual | 40.6 °F | 57.1 °F | 38.87 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |