Preston, Ontario climate data is summarized below. Average annual temperatures range from 37.4 °F (low) to 55.2 °F (high). Annual precipitation averages 34.4 Inches. Preston is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -22.9 °F | -18.9 °F | 279.4 in. |
| February | -23.7 °F | -19 °F | 355.6 in. |
| March | -20.5 °F | -15 °F | 1320.8 in. |
| April | -17 °F | -10.8 °F | 2082.8 in. |
| May | -13.5 °F | -6.9 °F | 2565.4 in. |
| June | -10.6 °F | -4.3 °F | 2946.4 in. |
| July | -9.5 °F | -3 °F | 3378.2 in. |
| August | -9.8 °F | -3.5 °F | 2743.2 in. |
| September | -12.1 °F | -5.8 °F | 2311.4 in. |
| October | -14.9 °F | -9.7 °F | 1905 in. |
| November | -18 °F | -13.5 °F | 1270 in. |
| December | -20.7 °F | -17.2 °F | 1041.4 in. |
| Annual | 37.4 °F | 55.2 °F | 34.41 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |