Seaforth, Ontario climate data is summarized below. Average annual temperatures range from 3.1 °C (low) to 12.6 °C (high). Annual precipitation averages 343 Millimeters. Seaforth 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 | -9.11 °C | -2.25 °C | 0 mm |
| February | -10.99 °C | -2.66 °C | 0 mm |
| March | -5.18 °C | 4.21 °C | 21 mm |
| April | 1.6 °C | 12.44 °C | 21 mm |
| May | 8.03 °C | 19.7 °C | 44 mm |
| June | 12.86 °C | 24.14 °C | 60 mm |
| July | 14.82 °C | 26.26 °C | 74 mm |
| August | 14.41 °C | 25.59 °C | 51 mm |
| September | 10.46 °C | 21.63 °C | 35 mm |
| October | 5.58 °C | 14.42 °C | 20 mm |
| November | -0.03 °C | 7.32 °C | 12 mm |
| December | -5.05 °C | 0.91 °C | 5 mm |
| Annual | 3.1 °C | 12.6 °C | 343 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |