Thorold, Ontario climate data is summarized below. Average annual temperatures range from 41.3 °F (low) to 56.7 °F (high). Annual precipitation averages 32.5 Inches. 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 | -21.5 °F | -17.9 °F | 685.8 in. |
| February | -22.2 °F | -18.3 °F | 609.6 in. |
| March | -19.2 °F | -14.5 °F | 1524 in. |
| April | -16.2 °F | -10.6 °F | 2082.8 in. |
| May | -12.9 °F | -6.7 °F | 2082.8 in. |
| June | -9.8 °F | -4.2 °F | 2387.6 in. |
| July | -8.1 °F | -2.8 °F | 2057.4 in. |
| August | -8.4 °F | -3.2 °F | 1828.8 in. |
| September | -10.8 °F | -5.5 °F | 2184.4 in. |
| October | -13.7 °F | -9.2 °F | 2286 in. |
| November | -16.9 °F | -12.8 °F | 1727.2 in. |
| December | -19.5 °F | -16.2 °F | 1498.6 in. |
| Annual | 41.3 °F | 56.7 °F | 32.47 in. |
| 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 : -5°F to 0°F |
| Current Drought Conditions | Normal |