Keswick, Ontario climate data is summarized below. Average annual temperatures range from 3.1 °C (low) to 11.9 °C (high). Annual precipitation averages 737 Millimeters. 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 | -10.07 °C | -2.52 °C | 9 mm |
| February | -11.41 °C | -3.06 °C | 0 mm |
| March | -5.42 °C | 3.33 °C | 37 mm |
| April | 1.37 °C | 11.13 °C | 58 mm |
| May | 7.34 °C | 18.49 °C | 90 mm |
| June | 12.57 °C | 23.09 °C | 106 mm |
| July | 15.59 °C | 25.77 °C | 137 mm |
| August | 15.25 °C | 24.95 °C | 115 mm |
| September | 11.24 °C | 20.7 °C | 70 mm |
| October | 6.05 °C | 13.82 °C | 53 mm |
| November | -0.01 °C | 7.14 °C | 38 mm |
| December | -5.64 °C | 0.34 °C | 24 mm |
| Annual | 3.1 °C | 11.9 °C | 737 mm |
| 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 : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |