| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7b: 5°F to 10°F Zone 7a: 0°F to 5°F | |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F | |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F | |
| 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: | 67b - Northern Shale Valleys | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 17236 - Mercersburg, PA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 22 | 29 | 39 | 47 | 57 | 61 | 59 | 51 | 39 | 32 | 24 | 40 |
| Avg Max Temp (°F) | 39 | 43 | 52 | 64 | 74 | 83 | 87 | 85 | 78 | 66 | 54 | 43 | 64 |
| Avg Precip (In.) | 2.85 | 2.44 | 3.65 | 3.69 | 4.3 | 4.15 | 3.7 | 3.86 | 3.7 | 3.46 | 3.4 | 3.13 | 42.32 |