| | Severn, MD | Manassas, VA | United States |
| Rainfall | 42.7 | 42.9 | 38.1 |
| Snowfall | 16.3 | 21.5 | 27.8 |
| Precipitation Days | 112.3 | 119.5 | 106.2 |
| Sunny | 208 | 196 | 205 |
| Avg. July High | 87.7 | 87.6 | 85.8 |
| Avg. Jan. Low | 24 | 23.7 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.3 | 7 |
| UV Index | 4 | 4.1 | 4.3 |
| Elevation ft. | 157 | 308 | 2443 |