Pennwyn, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.6 °F (low) to 62.7 °F (high). Annual precipitation averages 50.2 Inches. Pennwyn 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 | 22.3 °F | 38.4 °F | 3.61 in. |
| February | 23.4 °F | 40.9 °F | 2.87 in. |
| March | 31.0 °F | 49.7 °F | 4.14 in. |
| April | 41.2 °F | 62.4 °F | 3.9 in. |
| May | 51.2 °F | 71.9 °F | 3.95 in. |
| June | 60.5 °F | 80.9 °F | 5.0 in. |
| July | 65.4 °F | 85.3 °F | 5.09 in. |
| August | 63.6 °F | 83.5 °F | 4.39 in. |
| September | 56.4 °F | 77.1 °F | 5.16 in. |
| October | 45.0 °F | 65.1 °F | 4.55 in. |
| November | 35.2 °F | 53.5 °F | 3.45 in. |
| December | 27.7 °F | 43.1 °F | 4.13 in. |
| Annual | 43.6 °F | 62.7 °F | 50.24 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 | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |