| | Poolesville, MD | Rock Hall, MD | United States |
| Rainfall | 42 | 44.2 | 38.1 |
| Snowfall | 20.2 | 13.1 | 27.8 |
| Precipitation Days | 116.1 | 113.4 | 106.2 |
| Sunny | 203 | 206 | 205 |
| Avg. July High | 86.4 | 86.1 | 85.8 |
| Avg. Jan. Low | 24.6 | 27.2 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.4 | 7 |
| UV Index | 4.1 | 3.8 | 4.3 |
| Elevation ft. | 410 | 16 | 2443 |