| 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 6b: -5F to 0F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 64c - Piedmont Uplands |
| Heat Zone Days: | 31 - 45 days Over 86°F |
Annual Climate Data for ZIP Code 21758 - Knoxville, MD | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 22 | 24 | 32 | 41 | 51 | 60 | 64 | 62 | 55 | 43 | 34 | 27 | 43 |
| Avg Max Temp (°F) | 41 | 45 | 55 | 66 | 76 | 84 | 88 | 86 | 80 | 69 | 56 | 46 | 66 |
| Avg Precip (In.) | 2.85 | 2.56 | 3.5 | 3.28 | 3.65 | 3.6 | 3.64 | 3.53 | 3.59 | 2.91 | 3.12 | 2.92 | 39.15 |