Hamilton, Indiana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.2 °C (low) to 15.4 °C (high). Annual precipitation averages 968 Millimeters. Hamilton 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 | -8.4 °C | 0 °C | 61.21 mm |
| February | -7.5 °C | 2 °C | 53.09 mm |
| March | -2.9 °C | 8.1 °C | 63.25 mm |
| April | 2.8 °C | 15.5 °C | 92.2 mm |
| May | 9.3 °C | 21.8 °C | 109.47 mm |
| June | 14.7 °C | 26.8 °C | 98.81 mm |
| July | 16.4 °C | 28.8 °C | 95.5 mm |
| August | 15.3 °C | 27.7 °C | 100.08 mm |
| September | 11.2 °C | 24.4 °C | 82.04 mm |
| October | 5.2 °C | 17.3 °C | 74.42 mm |
| November | -0.4 °C | 9.3 °C | 76.2 mm |
| December | -5.2 °C | 2.7 °C | 61.72 mm |
| Annual | 4.2 °C | 15.4 °C | 967.99 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 | Dfb - Humid Continental Mild Summer, Wet All Year |