Blenheim, Ontario climate data is summarized below. Average annual temperatures range from 5 °C (low) to 13.7 °C (high). Annual precipitation averages 788 Millimeters. 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 | -7.54 °C | -0.87 °C | 21 mm |
| February | -8.97 °C | -1.16 °C | 18 mm |
| March | -2.68 °C | 5.92 °C | 61 mm |
| April | 2.99 °C | 13.04 °C | 78 mm |
| May | 9.47 °C | 19.8 °C | 85 mm |
| June | 14.93 °C | 25.08 °C | 89 mm |
| July | 17.27 °C | 27.09 °C | 115 mm |
| August | 16.6 °C | 26.2 °C | 79 mm |
| September | 12.32 °C | 22.13 °C | 77 mm |
| October | 7.23 °C | 15.81 °C | 64 mm |
| November | 1.48 °C | 8.74 °C | 56 mm |
| December | -3.34 °C | 2.6 °C | 45 mm |
| Annual | 5 °C | 13.7 °C | 788 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 |