Chantilly, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.3 °C (low) to 18.9 °C (high). Annual precipitation averages 1116.6 Millimeters. Chantilly is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4 °C | 6.2 °C | 75.69 mm |
| February | -3.2 °C | 7.9 °C | 66.29 mm |
| March | 0.7 °C | 12.7 °C | 94.23 mm |
| April | 6.2 °C | 19.2 °C | 83.31 mm |
| May | 11.6 °C | 23.7 °C | 113.28 mm |
| June | 16.7 °C | 28.4 °C | 112.01 mm |
| July | 19.3 °C | 30.9 °C | 109.22 mm |
| August | 18.3 °C | 30 °C | 90.17 mm |
| September | 14.6 °C | 26.3 °C | 106.43 mm |
| October | 7.7 °C | 19.9 °C | 95.25 mm |
| November | 1.9 °C | 13.8 °C | 80.52 mm |
| December | -1.7 °C | 8.3 °C | 90.17 mm |
| Annual | 7.3 °C | 18.9 °C | 1116.57 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |