Greencastle, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.8 °F (low) to 61.4 °F (high). Annual precipitation averages 46 Inches. Greencastle 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 | 19.0 °F | 35.0 °F | 3.23 in. |
| February | 21.6 °F | 39.6 °F | 2.64 in. |
| March | 30.7 °F | 50.4 °F | 3.38 in. |
| April | 40.7 °F | 62.0 °F | 4.73 in. |
| May | 51.5 °F | 72.1 °F | 4.98 in. |
| June | 60.6 °F | 80.6 °F | 5.33 in. |
| July | 63.3 °F | 83.2 °F | 4.69 in. |
| August | 61.0 °F | 82.2 °F | 3.12 in. |
| September | 54.0 °F | 76.9 °F | 3.67 in. |
| October | 42.5 °F | 64.6 °F | 3.55 in. |
| November | 32.4 °F | 51.0 °F | 3.67 in. |
| December | 24.0 °F | 39.3 °F | 3.02 in. |
| Annual | 41.8 °F | 61.4 °F | 46.01 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |