| | Swarthmore, PA | Potomac, MD | United States |
| Rainfall | 43.8 | 42 | 38.1 |
| Snowfall | 20 | 16.8 | 27.8 |
| Precipitation Days | 120.3 | 114 | 106.2 |
| Sunny | 208 | 201 | 205 |
| Avg. July High | 87.4 | 85.7 | 85.8 |
| Avg. Jan. Low | 26.2 | 25.3 | 21.7 |
| Comfort Index (higher=better) | 7.3 | 7.3 | 7 |
| UV Index | 3.8 | 4.1 | 4.3 |
| Elevation ft. | 131 | 361 | 2443 |