Downingtown, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.4 °C (low) to 17.7 °C (high). Annual precipitation averages 1259.8 Millimeters. Downingtown is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.3 °C | 4.4 °C | 91.44 mm |
| February | -5.8 °C | 5.7 °C | 75.44 mm |
| March | -1.6 °C | 10.5 °C | 109.22 mm |
| April | 4.2 °C | 17.6 °C | 97.03 mm |
| May | 9.7 °C | 22.8 °C | 100.33 mm |
| June | 15 °C | 27.7 °C | 115.57 mm |
| July | 17.8 °C | 30.1 °C | 118.36 mm |
| August | 16.8 °C | 29.3 °C | 112.01 mm |
| September | 12.5 °C | 25.7 °C | 128.27 mm |
| October | 5.9 °C | 19.1 °C | 116.08 mm |
| November | 0.2 °C | 12.6 °C | 85.85 mm |
| December | -3.2 °C | 6.9 °C | 110.24 mm |
| Annual | 5.4 °C | 17.7 °C | 1259.84 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |