Hamilton, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.9 °C (low) to 9.2 °C (high). Annual precipitation averages 556 Millimeters. Hamilton is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -19.9 °C | -10.5 °C | 15.24 mm |
| February | -18.3 °C | -7.9 °C | 13.72 mm |
| March | -10.4 °C | -0.7 °C | 21.34 mm |
| April | -1.7 °C | 9.8 °C | 27.43 mm |
| May | 5.4 °C | 18 °C | 80.52 mm |
| June | 11.8 °C | 23.4 °C | 98.81 mm |
| July | 13.9 °C | 25.9 °C | 82.04 mm |
| August | 12.2 °C | 25.7 °C | 70.61 mm |
| September | 7.4 °C | 20.6 °C | 57.4 mm |
| October | 0.5 °C | 11.5 °C | 43.43 mm |
| November | -7.7 °C | 1.2 °C | 24.38 mm |
| December | -15.7 °C | -7.1 °C | 21.08 mm |
| Annual | -1.9 °C | 9.2 °C | 556 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |