Blenheim, Ontario climate data is summarized below. Average annual temperatures range from 41 °F (low) to 56.7 °F (high). Annual precipitation averages 31 Inches. Blenheim 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 | -22 °F | -18.3 °F | 533.4 in. |
| February | -22.8 °F | -18.4 °F | 457.2 in. |
| March | -19.3 °F | -14.5 °F | 1549.4 in. |
| April | -16.1 °F | -10.5 °F | 1981.2 in. |
| May | -12.5 °F | -6.8 °F | 2159 in. |
| June | -9.5 °F | -3.8 °F | 2260.6 in. |
| July | -8.2 °F | -2.7 °F | 2921 in. |
| August | -8.6 °F | -3.2 °F | 2006.6 in. |
| September | -10.9 °F | -5.5 °F | 1955.8 in. |
| October | -13.8 °F | -9 °F | 1625.6 in. |
| November | -17 °F | -12.9 °F | 1422.4 in. |
| December | -19.6 °F | -16.3 °F | 1143 in. |
| Annual | 41 °F | 56.7 °F | 31.02 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 |