| | Chantilly, VA | Islip, NY | United States |
| Rainfall | 42.9 | 46.9 | 38.1 |
| Snowfall | 21.5 | 26.7 | 27.8 |
| Precipitation Days | 119.5 | 111.7 | 106.2 |
| Sunny | 197 | 206 | 205 |
| Avg. July High | 85.8 | 82.4 | 85.8 |
| Avg. Jan. Low | 23.5 | 23.4 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.2 | 7 |
| UV Index | 4 | 3.7 | 4.3 |
| Elevation ft. | 325 | 13 | 2443 |