Grundy, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.7 °C (low) to 19.4 °C (high). Annual precipitation averages 1191 Millimeters. Grundy is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.9 °C | 7.2 °C | 84.84 mm |
| February | -2.7 °C | 9.4 °C | 83.57 mm |
| March | 0.5 °C | 14.3 °C | 104.65 mm |
| April | 5.7 °C | 20.7 °C | 106.93 mm |
| May | 10.7 °C | 24.6 °C | 123.95 mm |
| June | 15.7 °C | 27.8 °C | 120.65 mm |
| July | 17.6 °C | 29.6 °C | 142.24 mm |
| August | 17.2 °C | 28.8 °C | 105.92 mm |
| September | 13.7 °C | 26.3 °C | 81.79 mm |
| October | 6.8 °C | 20.6 °C | 75.69 mm |
| November | 1 °C | 14.4 °C | 66.55 mm |
| December | -1.6 °C | 9.1 °C | 94.23 mm |
| Annual | 6.7 °C | 19.4 °C | 1191.01 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |