Dundas, Ontario climate data is summarized below. Average annual temperatures range from 40.1 °F (low) to 57 °F (high). Annual precipitation averages 38 Inches. Dundas is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -22 °F | -18 °F | 762 in. |
| February | -22.8 °F | -18.2 °F | 914.4 in. |
| March | -19.6 °F | -14.5 °F | 2133.6 in. |
| April | -16.3 °F | -10.6 °F | 2540 in. |
| May | -13 °F | -6.7 °F | 2540 in. |
| June | -10 °F | -3.9 °F | 2540 in. |
| July | -8.5 °F | -2.3 °F | 2641.6 in. |
| August | -8.8 °F | -2.8 °F | 2438.4 in. |
| September | -11.1 °F | -5.2 °F | 2184.4 in. |
| October | -14.2 °F | -9.1 °F | 2184.4 in. |
| November | -17.3 °F | -12.9 °F | 1803.4 in. |
| December | -19.9 °F | -16.4 °F | 1803.4 in. |
| Annual | 40.1 °F | 57 °F | 37.98 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |