Hamilton, Indiana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.6 °F (low) to 59.7 °F (high). Annual precipitation averages 38.1 Inches. 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 | 16.8 °F | 32.0 °F | 2.41 in. |
| February | 18.5 °F | 35.6 °F | 2.09 in. |
| March | 26.8 °F | 46.5 °F | 2.49 in. |
| April | 37.1 °F | 59.9 °F | 3.63 in. |
| May | 48.7 °F | 71.3 °F | 4.31 in. |
| June | 58.5 °F | 80.3 °F | 3.89 in. |
| July | 61.6 °F | 83.8 °F | 3.76 in. |
| August | 59.6 °F | 81.8 °F | 3.94 in. |
| September | 52.1 °F | 76.0 °F | 3.23 in. |
| October | 41.3 °F | 63.2 °F | 2.93 in. |
| November | 31.3 °F | 48.7 °F | 3.0 in. |
| December | 22.6 °F | 36.8 °F | 2.43 in. |
| Annual | 39.6 °F | 59.7 °F | 38.11 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |