| | Purcellville, VA | Olney, MD | United States |
| Rainfall | 42.1 | 43.3 | 38.1 |
| Snowfall | 21.3 | 15.8 | 27.8 |
| Precipitation Days | 115 | 111.9 | 106.2 |
| Sunny | 195 | 199 | 205 |
| Avg. July High | 86.4 | 87 | 85.8 |
| Avg. Jan. Low | 21 | 25 | 21.7 |
| Comfort Index (higher=better) | 7.2 | 7.3 | 7 |
| UV Index | 4 | 4.1 | 4.3 |
| Elevation ft. | 561 | 541 | 2443 |