London, Ontario climate data is summarized below. Average annual temperatures range from 39.5 °F (low) to 56.7 °F (high). Annual precipitation averages 19.8 Inches. London is located in USDA Plant Hardiness Zone 6b. 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 | -22.3 °F | -18.4 °F | 203.2 in. |
| February | -23.1 °F | -18.6 °F | 0 in. |
| March | -19.6 °F | -14.5 °F | 635 in. |
| April | -16.4 °F | -10.3 °F | 838.2 in. |
| May | -13 °F | -6.4 °F | 1473.2 in. |
| June | -10.2 °F | -3.8 °F | 2057.4 in. |
| July | -8.8 °F | -2.6 °F | 2311.4 in. |
| August | -9.1 °F | -3 °F | 2336.8 in. |
| September | -11.4 °F | -5.3 °F | 1371.6 in. |
| October | -14.3 °F | -9.2 °F | 838.2 in. |
| November | -17.4 °F | -13.1 °F | 508 in. |
| December | -19.9 °F | -16.7 °F | 228.6 in. |
| Annual | 39.5 °F | 56.7 °F | 19.83 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 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |