St. Catharines, Ontario climate data is summarized below. Average annual temperatures range from 42.5 °F (low) to 56.7 °F (high). Annual precipitation averages 31.9 Inches. St. Catharines is located in USDA Plant Hardiness Zone 7a. 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 °F | -17.6 °F | 838.2 in. |
| February | -21.7 °F | -18 °F | 711.2 in. |
| March | -18.8 °F | -14.5 °F | 1574.8 in. |
| April | -16 °F | -11 °F | 2108.2 in. |
| May | -12.9 °F | -7.2 °F | 1981.2 in. |
| June | -9.6 °F | -4.5 °F | 2260.6 in. |
| July | -7.8 °F | -2.8 °F | 2082.8 in. |
| August | -7.9 °F | -3.2 °F | 1752.6 in. |
| September | -10.2 °F | -5.5 °F | 1981.2 in. |
| October | -13.1 °F | -9.1 °F | 2159 in. |
| November | -16.4 °F | -12.7 °F | 1600.2 in. |
| December | -18.9 °F | -16 °F | 1498.6 in. |
| Annual | 42.5 °F | 56.7 °F | 31.85 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 7a : 0°F to 5°F |
| Current Drought Conditions | Normal |