De Kalb, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.2 °C (low) to 24.1 °C (high). Annual precipitation averages 1463.3 Millimeters. De Kalb is located in USDA Plant Hardiness Zone 8b. 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 | 1.4 °C | 13.6 °C | 136.91 mm |
| February | 3.1 °C | 16.2 °C | 138.94 mm |
| March | 6.6 °C | 20.4 °C | 143.26 mm |
| April | 10.4 °C | 24.4 °C | 144.53 mm |
| May | 15.3 °C | 28.1 °C | 114.05 mm |
| June | 19.4 °C | 31.5 °C | 120.9 mm |
| July | 20.9 °C | 32.8 °C | 130.81 mm |
| August | 20.4 °C | 32.7 °C | 111.51 mm |
| September | 17.6 °C | 30.1 °C | 85.85 mm |
| October | 11.1 °C | 25.3 °C | 95.25 mm |
| November | 5.4 °C | 19.2 °C | 104.9 mm |
| December | 2.4 °C | 14.8 °C | 136.4 mm |
| Annual | 11.2 °C | 24.1 °C | 1463.31 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 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |