Napoleon, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 15.8 °C (high). Annual precipitation averages 950.2 Millimeters. Napoleon 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 | -7.9 °C | 0.4 °C | 63.5 mm |
| February | -7 °C | 2.2 °C | 54.86 mm |
| March | -2.5 °C | 8.1 °C | 63.75 mm |
| April | 3.2 °C | 15.7 °C | 89.15 mm |
| May | 9.7 °C | 22.1 °C | 106.93 mm |
| June | 15.2 °C | 27.3 °C | 95.25 mm |
| July | 17 °C | 29.4 °C | 93.98 mm |
| August | 15.8 °C | 28.3 °C | 97.79 mm |
| September | 11.6 °C | 24.9 °C | 79.5 mm |
| October | 5.6 °C | 17.8 °C | 68.83 mm |
| November | 0 °C | 9.7 °C | 72.39 mm |
| December | -4.6 °C | 3.2 °C | 64.26 mm |
| Annual | 4.7 °C | 15.8 °C | 950.19 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 |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |