Delphi, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.5 °C (low) to 16.7 °C (high). Annual precipitation averages 1022.9 Millimeters. Delphi is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.5 °C | 1.2 °C | 65.28 mm |
| February | -5.8 °C | 3.4 °C | 53.09 mm |
| March | -0.9 °C | 9.9 °C | 72.14 mm |
| April | 4.8 °C | 17.3 °C | 99.31 mm |
| May | 10.7 °C | 23.3 °C | 110.49 mm |
| June | 15.9 °C | 28 °C | 121.16 mm |
| July | 17.4 °C | 29.4 °C | 118.62 mm |
| August | 16.6 °C | 28.7 °C | 91.69 mm |
| September | 12.3 °C | 25.9 °C | 77.22 mm |
| October | 6.1 °C | 18.8 °C | 76.71 mm |
| November | 0.7 °C | 10.6 °C | 76.96 mm |
| December | -4.3 °C | 3.9 °C | 60.2 mm |
| Annual | 5.5 °C | 16.7 °C | 1022.87 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |