Harrisburg, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.6 °C (low) to 17 °C (high). Annual precipitation averages 1135.4 Millimeters. Harrisburg 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 | -5.3 °C | 3.2 °C | 81.53 mm |
| February | -4.7 °C | 4.8 °C | 65.53 mm |
| March | -0.4 °C | 9.8 °C | 93.98 mm |
| April | 5.4 °C | 16.9 °C | 91.19 mm |
| May | 11.1 °C | 22.4 °C | 103.89 mm |
| June | 16.2 °C | 27.4 °C | 107.44 mm |
| July | 18.7 °C | 30.1 °C | 108.71 mm |
| August | 17.8 °C | 29 °C | 100.58 mm |
| September | 13.7 °C | 25.1 °C | 117.35 mm |
| October | 7.3 °C | 18.2 °C | 100.08 mm |
| November | 1.7 °C | 11.8 °C | 78.74 mm |
| December | -2.4 °C | 5.8 °C | 86.36 mm |
| Annual | 6.6 °C | 17 °C | 1135.38 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |