| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F | |
| 2012 Hardiness Zone: | Zone 7a: 0°F to 5°F | |
| 1990 Hardiness Zone: | Zone 6b: -5F to 0F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | Apr. 21 - Apr. 30 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 64c - Piedmont Uplands | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 21755 - Jefferson, MD | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 23 | 25 | 33 | 42 | 52 | 60 | 65 | 63 | 56 | 44 | 36 | 28 | 44 |
| Avg Max Temp (°F) | 41 | 45 | 55 | 66 | 76 | 83 | 87 | 86 | 79 | 68 | 56 | 45 | 66 |
| Avg Precip (In.) | 3.15 | 2.64 | 3.68 | 3.38 | 4.26 | 3.88 | 3.71 | 3.38 | 3.88 | 3.39 | 3.31 | 3.09 | 41.77 |