Keswick, Ontario climate data is summarized below. Average annual temperatures range from 37.5 °F (low) to 53.5 °F (high). Annual precipitation averages 29 Inches. Keswick is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -23.4 °F | -19.2 °F | 228.6 in. |
| February | -24.1 °F | -19.5 °F | 0 in. |
| March | -20.8 °F | -15.9 °F | 939.8 in. |
| April | -17 °F | -11.6 °F | 1473.2 in. |
| May | -13.7 °F | -7.5 °F | 2286 in. |
| June | -10.8 °F | -5 °F | 2692.4 in. |
| July | -9.1 °F | -3.5 °F | 3479.8 in. |
| August | -9.3 °F | -3.9 °F | 2921 in. |
| September | -11.5 °F | -6.3 °F | 1778 in. |
| October | -14.4 °F | -10.1 °F | 1346.2 in. |
| November | -17.8 °F | -13.8 °F | 965.2 in. |
| December | -20.9 °F | -17.6 °F | 609.6 in. |
| Annual | 37.5 °F | 53.5 °F | 29.01 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |