Flatwoods, West Virginia has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.3 °C (low) to 18.2 °C (high). Annual precipitation averages 1307.1 Millimeters. Flatwoods is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.7 °C | 5.2 °C | 95.76 mm |
| February | -4.8 °C | 7.1 °C | 89.15 mm |
| March | -1.1 °C | 12.2 °C | 111 mm |
| April | 4.1 °C | 19.3 °C | 103.38 mm |
| May | 9.6 °C | 23.4 °C | 134.37 mm |
| June | 14.3 °C | 27.6 °C | 134.62 mm |
| July | 16.7 °C | 29.2 °C | 152.4 mm |
| August | 16 °C | 28.7 °C | 113.28 mm |
| September | 12.3 °C | 25.6 °C | 90.17 mm |
| October | 5.6 °C | 19.6 °C | 93.22 mm |
| November | -0.1 °C | 13 °C | 84.07 mm |
| December | -3.2 °C | 7.3 °C | 105.66 mm |
| Annual | 5.3 °C | 18.2 °C | 1307.08 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |