Brockville, Ontario climate data is summarized below. Average annual temperatures range from 2.5 °C (low) to 12.4 °C (high). Annual precipitation averages 525 Millimeters. 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 | -12 °C | -2.95 °C | 3 mm |
| February | -12.79 °C | -2.89 °C | 7 mm |
| March | -6.21 °C | 3.93 °C | 30 mm |
| April | 1.73 °C | 12.33 °C | 62 mm |
| May | 8.04 °C | 19.6 °C | 58 mm |
| June | 13.03 °C | 23.76 °C | 60 mm |
| July | 15.68 °C | 26.29 °C | 71 mm |
| August | 14.91 °C | 25.52 °C | 64 mm |
| September | 10.34 °C | 21.41 °C | 43 mm |
| October | 5.14 °C | 14.34 °C | 65 mm |
| November | -0.63 °C | 7.51 °C | 39 mm |
| December | -7.28 °C | -0.08 °C | 23 mm |
| Annual | 2.5 °C | 12.4 °C | 525 mm |
| 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 : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |