| | Chantilly, VA | Accokeek, MD | United States |
| Rainfall | 42.9 | 42.9 | 38.1 |
| Snowfall | 21.5 | 15.3 | 27.8 |
| Precipitation Days | 119.5 | 109.5 | 106.2 |
| Sunny | 197 | 202 | 205 |
| Avg. July High | 85.8 | 87 | 85.8 |
| Avg. Jan. Low | 23.5 | 27.8 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.5 | 7 |
| UV Index | 4 | 4.3 | 4.3 |
| Elevation ft. | 325 | 194 | 2443 |