Adelphi, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.8 °C (low) to 17.2 °C (high). Annual precipitation averages 1051.8 Millimeters. Adelphi is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6 °C | 3.2 °C | 74.42 mm |
| February | -5.1 °C | 5.1 °C | 66.29 mm |
| March | -0.8 °C | 10.6 °C | 85.34 mm |
| April | 5 °C | 17.7 °C | 105.16 mm |
| May | 10.8 °C | 22.9 °C | 113.28 mm |
| June | 15.7 °C | 27.4 °C | 110.74 mm |
| July | 17.6 °C | 29.1 °C | 106.43 mm |
| August | 16.4 °C | 28.6 °C | 89.66 mm |
| September | 12.3 °C | 25.6 °C | 76.2 mm |
| October | 6 °C | 18.7 °C | 75.95 mm |
| November | 0.6 °C | 11.6 °C | 76.2 mm |
| December | -3.2 °C | 5.7 °C | 72.14 mm |
| Annual | 5.8 °C | 17.2 °C | 1051.81 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |