Hamilton, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.2 °C (low) to 13.8 °C (high). Annual precipitation averages 1140 Millimeters. Hamilton is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.8 °C | -0.6 °C | 81.28 mm |
| February | -10.1 °C | 0.8 °C | 67.82 mm |
| March | -5.9 °C | 5.3 °C | 90.93 mm |
| April | 0.6 °C | 13 °C | 92.46 mm |
| May | 6.8 °C | 20.2 °C | 97.54 mm |
| June | 11.9 °C | 24.8 °C | 115.82 mm |
| July | 14.4 °C | 27.1 °C | 108.46 mm |
| August | 13.6 °C | 26.2 °C | 112.01 mm |
| September | 9.6 °C | 22.5 °C | 98.3 mm |
| October | 3.8 °C | 15.2 °C | 100.33 mm |
| November | -1.5 °C | 8.3 °C | 87.88 mm |
| December | -6.3 °C | 2.2 °C | 87.12 mm |
| Annual | 2.2 °C | 13.8 °C | 1139.95 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |