Wiarton, Ontario climate data is summarized below. Average annual temperatures range from 3 °C (low) to 11.2 °C (high). Annual precipitation averages 707 Millimeters. Wiarton 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.93 °C | -2.17 °C | 0 mm |
| February | -10.71 °C | -3.12 °C | 0 mm |
| March | -5.25 °C | 2.89 °C | 32 mm |
| April | 0.9 °C | 9.88 °C | 77 mm |
| May | 6.34 °C | 16.46 °C | 95 mm |
| June | 11.48 °C | 21.2 °C | 89 mm |
| July | 14.59 °C | 23.86 °C | 58 mm |
| August | 14.58 °C | 23.77 °C | 80 mm |
| September | 10.73 °C | 19.9 °C | 83 mm |
| October | 6.23 °C | 13.64 °C | 112 mm |
| November | 0.65 °C | 7.31 °C | 62 mm |
| December | -4.5 °C | 0.95 °C | 19 mm |
| Annual | 3 °C | 11.2 °C | 707 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |