Berwyn, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.9 °C (low) to 17 °C (high). Annual precipitation averages 1218.2 Millimeters. Berwyn 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 | -6.1 °C | 3.6 °C | 87.88 mm |
| February | -5.4 °C | 5.1 °C | 73.66 mm |
| March | -1.2 °C | 9.9 °C | 105.16 mm |
| April | 4.7 °C | 16.6 °C | 95 mm |
| May | 10.1 °C | 21.9 °C | 99.57 mm |
| June | 15.3 °C | 27 °C | 113.03 mm |
| July | 18.1 °C | 29.4 °C | 117.6 mm |
| August | 17.3 °C | 28.6 °C | 113.79 mm |
| September | 13.1 °C | 24.9 °C | 118.36 mm |
| October | 6.9 °C | 18.1 °C | 103.38 mm |
| November | 1.2 °C | 12 °C | 81.79 mm |
| December | -2.9 °C | 6.3 °C | 108.97 mm |
| Annual | 5.9 °C | 17 °C | 1218.19 mm |
| 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 : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |