Napanee, Ontario climate data is summarized below. Average annual temperatures range from 2.7 °C (low) to 13.2 °C (high). Annual precipitation averages 668 Millimeters. 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 | -11.07 °C | -2.15 °C | 11 mm |
| February | -11.88 °C | -2.25 °C | 7 mm |
| March | -5.33 °C | 4.79 °C | 43 mm |
| April | 1.8 °C | 12.98 °C | 66 mm |
| May | 8.1 °C | 20.67 °C | 72 mm |
| June | 13.22 °C | 24.93 °C | 82 mm |
| July | 15.63 °C | 27.45 °C | 110 mm |
| August | 14.8 °C | 26.5 °C | 92 mm |
| September | 9.99 °C | 21.95 °C | 58 mm |
| October | 4.8 °C | 14.69 °C | 59 mm |
| November | -1.05 °C | 7.88 °C | 39 mm |
| December | -6.78 °C | 0.72 °C | 29 mm |
| Annual | 2.7 °C | 13.2 °C | 668 mm |
| 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 : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |