| | Herndon, VA | Lanham, MD | United States |
| Rainfall | 42.9 | 43.4 | 38.1 |
| Snowfall | 21.5 | 14.8 | 27.8 |
| Precipitation Days | 119.5 | 108.5 | 106.2 |
| Sunny | 201 | 203 | 205 |
| Avg. July High | 85.8 | 87.9 | 85.8 |
| Avg. Jan. Low | 23.5 | 24.1 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.3 | 7 |
| UV Index | 4 | 4.3 | 4.3 |
| Elevation ft. | 361 | 151 | 2443 |