Fairmount, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.2 °C (low) to 11.4 °C (high). Annual precipitation averages 645.7 Millimeters. Fairmount is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -17.3 °C | -7.4 °C | 18.03 mm |
| February | -15.4 °C | -4.9 °C | 16.51 mm |
| March | -7.6 °C | 2.3 °C | 27.43 mm |
| April | 0.1 °C | 11.8 °C | 52.32 mm |
| May | 7.3 °C | 19.8 °C | 79.25 mm |
| June | 13.6 °C | 25.1 °C | 105.41 mm |
| July | 15.7 °C | 27.5 °C | 96.77 mm |
| August | 13.9 °C | 26.7 °C | 73.41 mm |
| September | 9 °C | 22.2 °C | 71.63 mm |
| October | 1.8 °C | 13.7 °C | 62.23 mm |
| November | -5.8 °C | 4 °C | 22.61 mm |
| December | -13.2 °C | -3.9 °C | 20.07 mm |
| Annual | 0.2 °C | 11.4 °C | 645.67 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |