Keo, Arkansas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.2 °C (low) to 22.2 °C (high). Annual precipitation averages 1304.3 Millimeters. Keo is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.1 °C | 10.1 °C | 99.57 mm |
| February | 1.7 °C | 12.7 °C | 103.89 mm |
| March | 5.8 °C | 17.5 °C | 126.49 mm |
| April | 10.8 °C | 22.7 °C | 142.24 mm |
| May | 16.2 °C | 26.9 °C | 125.98 mm |
| June | 20.7 °C | 31 °C | 85.09 mm |
| July | 22.3 °C | 32.6 °C | 92.2 mm |
| August | 21.5 °C | 32.3 °C | 77.98 mm |
| September | 17.4 °C | 29.2 °C | 88.65 mm |
| October | 10.8 °C | 23.6 °C | 106.17 mm |
| November | 5.2 °C | 16.7 °C | 116.59 mm |
| December | 1.5 °C | 11.6 °C | 139.45 mm |
| Annual | 11.2 °C | 22.2 °C | 1304.3 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |