Dumfries, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.2 °C (low) to 19.5 °C (high). Annual precipitation averages 1094.8 Millimeters. Dumfries is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.2 °C | 7.1 °C | 77.47 mm |
| February | -2.3 °C | 8.9 °C | 66.8 mm |
| March | 1.4 °C | 13.3 °C | 95.25 mm |
| April | 7.1 °C | 19.8 °C | 78.23 mm |
| May | 12.6 °C | 24.1 °C | 98.04 mm |
| June | 17.6 °C | 28.7 °C | 105.92 mm |
| July | 20.3 °C | 31.2 °C | 111.51 mm |
| August | 19.2 °C | 30.1 °C | 94.23 mm |
| September | 15.5 °C | 26.6 °C | 107.7 mm |
| October | 8.6 °C | 20.4 °C | 92.46 mm |
| November | 2.5 °C | 14.4 °C | 78.49 mm |
| December | -1 °C | 9.4 °C | 88.65 mm |
| Annual | 8.2 °C | 19.5 °C | 1094.75 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |