| | Potomac Mills, VA | Merrifield, VA | United States |
| Rainfall | 42.3 | 42.7 | 38.1 |
| Snowfall | 17.8 | 21.3 | 27.8 |
| Precipitation Days | 117.9 | 116.7 | 106.2 |
| Sunny | 198 | 202 | 205 |
| Avg. July High | 86.6 | 86.2 | 85.8 |
| Avg. Jan. Low | 23.7 | 24.2 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.3 | 7 |
| UV Index | 4 | 4 | 4.3 |
| Elevation ft. | 203 | 361 | 2443 |