Gillham, Arkansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10 °C (low) to 22.7 °C (high). Annual precipitation averages 1410.5 Millimeters. Gillham is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.1 °C | 11.3 °C | 99.06 mm |
| February | 0.7 °C | 13.7 °C | 99.06 mm |
| March | 4.6 °C | 18.2 °C | 126.75 mm |
| April | 9 °C | 22.7 °C | 141.73 mm |
| May | 14.5 °C | 26.4 °C | 157.99 mm |
| June | 19.1 °C | 30.7 °C | 109.22 mm |
| July | 20.9 °C | 33.1 °C | 104.39 mm |
| August | 20.5 °C | 33.3 °C | 86.11 mm |
| September | 16.6 °C | 29.8 °C | 108.2 mm |
| October | 10 °C | 23.8 °C | 125.98 mm |
| November | 4.4 °C | 17.3 °C | 122.17 mm |
| December | 0.4 °C | 12.3 °C | 129.79 mm |
| Annual | 10 °C | 22.7 °C | 1410.45 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |