Cornwall, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.1 °F (low) to 62.5 °F (high). Annual precipitation averages 47.5 Inches. Cornwall is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 20.9 °F | 37.8 °F | 3.3 in. |
| February | 21.9 °F | 40.7 °F | 2.57 in. |
| March | 29.6 °F | 49.6 °F | 3.85 in. |
| April | 39.8 °F | 62.5 °F | 3.7 in. |
| May | 50.0 °F | 72.4 °F | 4.07 in. |
| June | 59.4 °F | 80.6 °F | 4.56 in. |
| July | 63.7 °F | 85.3 °F | 4.71 in. |
| August | 62.0 °F | 83.4 °F | 4.14 in. |
| September | 54.9 °F | 76.6 °F | 4.96 in. |
| October | 43.3 °F | 65.0 °F | 4.44 in. |
| November | 33.6 °F | 53.3 °F | 3.44 in. |
| December | 26.3 °F | 42.5 °F | 3.77 in. |
| Annual | 42.1 °F | 62.5 °F | 47.51 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |