South Middleton, Ontario climate data is summarized below. Average annual temperatures range from 38.9 °F (low) to 56.1 °F (high). Annual precipitation averages 19.9 Inches. South Middleton 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 | -22.3 °F | -18.3 °F | 304.8 in. |
| February | -23.4 °F | -18.7 °F | 50.8 in. |
| March | -19.9 °F | -14.8 °F | 736.6 in. |
| April | -16.6 °F | -10.6 °F | 939.8 in. |
| May | -13.2 °F | -6.9 °F | 1346.2 in. |
| June | -10.3 °F | -4.1 °F | 1651 in. |
| July | -9.1 °F | -2.9 °F | 2057.4 in. |
| August | -9.4 °F | -3.4 °F | 1981.2 in. |
| September | -11.7 °F | -5.7 °F | 1828.8 in. |
| October | -14.5 °F | -9.4 °F | 939.8 in. |
| November | -17.5 °F | -13 °F | 635 in. |
| December | -19.9 °F | -16.5 °F | 355.6 in. |
| Annual | 38.9 °F | 56.1 °F | 19.88 in. |
| 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 : -10°F to -5°F |
| Current Drought Conditions | Normal |