Thorold, Ontario climate data is summarized below. Average annual temperatures range from 5.2 °C (low) to 13.7 °C (high). Annual precipitation averages 825 Millimeters. Thorold is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.72 °C | -0.27 °C | 27 mm |
| February | -7.93 °C | -0.96 °C | 24 mm |
| March | -2.49 °C | 5.97 °C | 60 mm |
| April | 2.9 °C | 12.86 °C | 82 mm |
| May | 8.84 °C | 19.88 °C | 82 mm |
| June | 14.4 °C | 24.5 °C | 94 mm |
| July | 17.36 °C | 27 °C | 81 mm |
| August | 16.88 °C | 26.33 °C | 72 mm |
| September | 12.64 °C | 22.12 °C | 86 mm |
| October | 7.32 °C | 15.38 °C | 90 mm |
| November | 1.58 °C | 8.88 °C | 68 mm |
| December | -3.01 °C | 2.8 °C | 59 mm |
| Annual | 5.2 °C | 13.7 °C | 825 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |