Castine, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.2 °C (low) to 16.1 °C (high). Annual precipitation averages 1042.4 Millimeters. Castine 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 | -7.4 °C | 1.4 °C | 75.95 mm |
| February | -5.9 °C | 3.6 °C | 57.66 mm |
| March | -1.4 °C | 9.4 °C | 84.33 mm |
| April | 4.3 °C | 16.6 °C | 108.46 mm |
| May | 10.6 °C | 22.2 °C | 112.27 mm |
| June | 15.6 °C | 26.8 °C | 119.13 mm |
| July | 17.2 °C | 28.4 °C | 98.3 mm |
| August | 16.1 °C | 27.9 °C | 77.72 mm |
| September | 11.9 °C | 24.8 °C | 74.42 mm |
| October | 5.8 °C | 18.1 °C | 76.45 mm |
| November | 0.2 °C | 10.4 °C | 78.99 mm |
| December | -4.3 °C | 4 °C | 78.74 mm |
| Annual | 5.2 °C | 16.1 °C | 1042.42 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |