Duncan, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 53.1 °F (low) to 72.8 °F (high). Annual precipitation averages 55.3 Inches. Duncan is located in USDA Plant Hardiness Zone 8b. 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 | 33.6 °F | 50.7 °F | 4.96 in. |
| February | 36.4 °F | 55.2 °F | 5.23 in. |
| March | 44.0 °F | 63.9 °F | 5.23 in. |
| April | 52.8 °F | 73.4 °F | 6.02 in. |
| May | 62.5 °F | 81.6 °F | 5.21 in. |
| June | 69.8 °F | 88.4 °F | 4.18 in. |
| July | 72.4 °F | 90.6 °F | 3.99 in. |
| August | 70.8 °F | 90.7 °F | 3.13 in. |
| September | 64.1 °F | 86.3 °F | 3.21 in. |
| October | 52.5 °F | 75.8 °F | 3.88 in. |
| November | 42.2 °F | 63.0 °F | 4.51 in. |
| December | 36.2 °F | 53.4 °F | 5.76 in. |
| Annual | 53.1 °F | 72.8 °F | 55.31 in. |
| 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 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |