Richmond Hill, Ontario climate data is summarized below. Average annual temperatures range from 38 °F (low) to 54.8 °F (high). Annual precipitation averages 35.4 Inches. Richmond Hill 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 | -23 °F | -18.9 °F | 457.2 in. |
| February | -23.6 °F | -19.1 °F | 330.2 in. |
| March | -20.5 °F | -15.2 °F | 1498.6 in. |
| April | -16.8 °F | -11.1 °F | 2311.4 in. |
| May | -13.2 °F | -6.9 °F | 2641.6 in. |
| June | -10.4 °F | -4.4 °F | 2997.2 in. |
| July | -9 °F | -2.9 °F | 2870.2 in. |
| August | -9.3 °F | -3.4 °F | 2921 in. |
| September | -11.8 °F | -5.9 °F | 2108.2 in. |
| October | -14.7 °F | -10 °F | 1981.2 in. |
| November | -18 °F | -13.7 °F | 1549.4 in. |
| December | -20.8 °F | -17.3 °F | 1193.8 in. |
| Annual | 38 °F | 54.8 °F | 35.43 in. |
| 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 : -10°F to -5°F |
| Current Drought Conditions | Normal |