Napanee, Ontario climate data is summarized below. Average annual temperatures range from 36.8 °F (low) to 55.7 °F (high). Annual precipitation averages 26.3 Inches. Napanee is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -23.9 °F | -19 °F | 279.4 in. |
| February | -24.4 °F | -19 °F | 177.8 in. |
| March | -20.7 °F | -15.1 °F | 1092.2 in. |
| April | -16.8 °F | -10.6 °F | 1676.4 in. |
| May | -13.3 °F | -6.3 °F | 1828.8 in. |
| June | -10.4 °F | -3.9 °F | 2082.8 in. |
| July | -9.1 °F | -2.5 °F | 2794 in. |
| August | -9.6 °F | -3.1 °F | 2336.8 in. |
| September | -12.2 °F | -5.6 °F | 1473.2 in. |
| October | -15.1 °F | -9.6 °F | 1498.6 in. |
| November | -18.4 °F | -13.4 °F | 990.6 in. |
| December | -21.5 °F | -17.4 °F | 736.6 in. |
| Annual | 36.8 °F | 55.7 °F | 26.29 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |