Thessalon, Ontario climate data is summarized below. Average annual temperatures range from 1.4 °C (low) to 9.1 °C (high). Annual precipitation averages 478 Millimeters. Thessalon is located in USDA Plant Hardiness Zone 5a. 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 | -13.1 °C | -4.86 °C | 0 mm |
| February | -14.49 °C | -4.79 °C | 0 mm |
| March | -8.36 °C | 0.77 °C | 6 mm |
| April | -0.9 °C | 6.55 °C | 23 mm |
| May | 5.61 °C | 13.99 °C | 50 mm |
| June | 10.91 °C | 18.97 °C | 78 mm |
| July | 14.16 °C | 22.19 °C | 81 mm |
| August | 14.7 °C | 22.3 °C | 86 mm |
| September | 10.73 °C | 18.34 °C | 68 mm |
| October | 5.54 °C | 12.04 °C | 52 mm |
| November | -0.2 °C | 5.53 °C | 22 mm |
| December | -8.31 °C | -1.55 °C | 12 mm |
| Annual | 1.4 °C | 9.1 °C | 478 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |