Charlestown, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 8 °C (low) to 19.3 °C (high). Annual precipitation averages 1261.6 Millimeters. Charlestown is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.8 °C | 5.3 °C | 89.15 mm |
| February | -2.4 °C | 7.9 °C | 84.07 mm |
| March | 1.8 °C | 13.5 °C | 113.79 mm |
| April | 7.3 °C | 20 °C | 126.49 mm |
| May | 13.2 °C | 24.9 °C | 130.56 mm |
| June | 17.8 °C | 29.1 °C | 130.05 mm |
| July | 19.7 °C | 30.8 °C | 107.7 mm |
| August | 18.9 °C | 30.5 °C | 93.73 mm |
| September | 14.7 °C | 27.1 °C | 91.19 mm |
| October | 8.2 °C | 21 °C | 93.22 mm |
| November | 2.4 °C | 13.6 °C | 92.96 mm |
| December | -1.5 °C | 7.6 °C | 108.71 mm |
| Annual | 8 °C | 19.3 °C | 1261.62 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |