Courtland, Ontario climate data is summarized below. Average annual temperatures range from 3.7 °C (low) to 13.4 °C (high). Annual precipitation averages 509 Millimeters. Courtland 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 | -8.32 °C | -1.14 °C | 12 mm |
| February | -10 °C | -1.65 °C | 2 mm |
| March | -3.85 °C | 5.44 °C | 29 mm |
| April | 2.09 °C | 12.99 °C | 38 mm |
| May | 8.22 °C | 19.8 °C | 52 mm |
| June | 13.52 °C | 24.79 °C | 69 mm |
| July | 15.48 °C | 26.91 °C | 82 mm |
| August | 14.84 °C | 26.09 °C | 79 mm |
| September | 10.69 °C | 21.95 °C | 71 mm |
| October | 5.68 °C | 15.11 °C | 36 mm |
| November | 0.3 °C | 8.44 °C | 25 mm |
| December | -4.12 °C | 2.06 °C | 14 mm |
| Annual | 3.7 °C | 13.4 °C | 509 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |