| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | May 11 - May 20 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 67b - Northern Shale Valleys | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 21561 - Swanton, MD | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 18 | 26 | 34 | 44 | 53 | 57 | 56 | 50 | 39 | 30 | 22 | 37 |
| Avg Max Temp (°F) | 34 | 37 | 46 | 57 | 67 | 74 | 77 | 75 | 69 | 59 | 47 | 38 | 57 |
| Avg Precip (In.) | 3.59 | 3.2 | 4.12 | 3.9 | 4.68 | 4.18 | 4.74 | 4.07 | 3.49 | 3.01 | 3.41 | 3.48 | 45.87 |