Fairmont, West Virginia has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.5 °C (low) to 17.6 °C (high). Annual precipitation averages 1222.3 Millimeters. Fairmont is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.8 °C | 4 °C | 93.73 mm |
| February | -4.8 °C | 5.8 °C | 83.31 mm |
| March | -1.2 °C | 11.1 °C | 103.12 mm |
| April | 4.3 °C | 18.7 °C | 102.11 mm |
| May | 9.8 °C | 23.4 °C | 124.71 mm |
| June | 14.7 °C | 27.4 °C | 120.65 mm |
| July | 17.1 °C | 29.3 °C | 130.56 mm |
| August | 16.4 °C | 28.8 °C | 100.58 mm |
| September | 12.4 °C | 25.6 °C | 93.73 mm |
| October | 5.8 °C | 18.9 °C | 85.34 mm |
| November | 0.4 °C | 11.8 °C | 86.87 mm |
| December | -3.1 °C | 6.1 °C | 97.54 mm |
| Annual | 5.5 °C | 17.6 °C | 1222.25 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |