Brockville, Ontario climate data is summarized below. Average annual temperatures range from 36.5 °F (low) to 54.3 °F (high). Annual precipitation averages 20.7 Inches. Brockville is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -24.4 °F | -19.4 °F | 76.2 in. |
| February | -24.9 °F | -19.4 °F | 177.8 in. |
| March | -21.2 °F | -15.6 °F | 762 in. |
| April | -16.8 °F | -10.9 °F | 1574.8 in. |
| May | -13.3 °F | -6.9 °F | 1473.2 in. |
| June | -10.5 °F | -4.6 °F | 1524 in. |
| July | -9.1 °F | -3.2 °F | 1803.4 in. |
| August | -9.5 °F | -3.6 °F | 1625.6 in. |
| September | -12 °F | -5.9 °F | 1092.2 in. |
| October | -14.9 °F | -9.8 °F | 1651 in. |
| November | -18.1 °F | -13.6 °F | 990.6 in. |
| December | -21.8 °F | -17.8 °F | 584.2 in. |
| Annual | 36.5 °F | 54.3 °F | 20.68 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |