| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F | |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F | |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F | |
| Average First Frost Date: | Oct. 21 - Oct. 31 | |
| Average Last Frost Date: | May 1 - May 10 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 64c - Piedmont Uplands | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 21771 - Mount Airy, MD | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 23 | 24 | 32 | 40 | 50 | 59 | 64 | 62 | 55 | 44 | 35 | 27 | 43 |
| Avg Max Temp (°F) | 39 | 43 | 53 | 64 | 74 | 82 | 86 | 84 | 77 | 66 | 54 | 44 | 64 |
| Avg Precip (In.) | 3.35 | 2.65 | 3.76 | 3.4 | 4.37 | 4.21 | 3.66 | 3.38 | 3.99 | 3.53 | 3.56 | 3.22 | 43.07 |