Port Gibson, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 54.1 °F (low) to 76.2 °F (high). Annual precipitation averages 57.7 Inches. Port Gibson 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 | 36.2 °F | 57.0 °F | 5.78 in. |
| February | 39.0 °F | 61.6 °F | 5.37 in. |
| March | 46.2 °F | 69.4 °F | 5.71 in. |
| April | 53.5 °F | 76.6 °F | 5.47 in. |
| May | 62.2 °F | 83.6 °F | 4.45 in. |
| June | 69.3 °F | 89.4 °F | 4.62 in. |
| July | 71.8 °F | 91.7 °F | 4.52 in. |
| August | 70.8 °F | 92.1 °F | 3.93 in. |
| September | 64.9 °F | 87.6 °F | 3.82 in. |
| October | 53.3 °F | 78.5 °F | 3.94 in. |
| November | 43.6 °F | 67.5 °F | 4.69 in. |
| December | 38.2 °F | 59.5 °F | 5.38 in. |
| Annual | 54.1 °F | 76.2 °F | 57.68 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 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 | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |