Harrisburg, Arkansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.6 °C (low) to 21.4 °C (high). Annual precipitation averages 1302.3 Millimeters. Harrisburg is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1 °C | 8.3 °C | 96.77 mm |
| February | 0.7 °C | 10.9 °C | 104.65 mm |
| March | 5.1 °C | 15.9 °C | 124.97 mm |
| April | 10.2 °C | 21.9 °C | 142.75 mm |
| May | 15.7 °C | 26.6 °C | 131.83 mm |
| June | 20.2 °C | 31.1 °C | 101.09 mm |
| July | 21.9 °C | 32.4 °C | 99.82 mm |
| August | 20.9 °C | 31.9 °C | 77.47 mm |
| September | 16.8 °C | 29 °C | 76.71 mm |
| October | 10.4 °C | 23.1 °C | 108.97 mm |
| November | 5 °C | 15.6 °C | 110.74 mm |
| December | 0.7 °C | 9.9 °C | 126.49 mm |
| Annual | 10.6 °C | 21.4 °C | 1302.26 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |