Rossmore, West Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.2 °C (low) to 19.8 °C (high). Annual precipitation averages 1259.3 Millimeters. Rossmore is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.8 °C | 6.8 °C | 88.14 mm |
| February | -2.4 °C | 9.3 °C | 88.14 mm |
| March | 0.9 °C | 14.2 °C | 113.79 mm |
| April | 6.1 °C | 21.2 °C | 109.73 mm |
| May | 11.6 °C | 25.3 °C | 131.06 mm |
| June | 16.3 °C | 29.1 °C | 126.49 mm |
| July | 18.6 °C | 30.7 °C | 153.92 mm |
| August | 18 °C | 30.2 °C | 101.35 mm |
| September | 14.1 °C | 27.2 °C | 85.85 mm |
| October | 7.3 °C | 20.9 °C | 79.25 mm |
| November | 1.3 °C | 14.3 °C | 75.18 mm |
| December | -1.6 °C | 8.8 °C | 106.43 mm |
| Annual | 7.2 °C | 19.8 °C | 1259.33 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |