Port Sulphur, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 63.1 °F (low) to 76.9 °F (high). Annual precipitation averages 66.2 Inches. Port Sulphur is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 46.5 °F | 61.6 °F | 5.18 in. |
| February | 49.5 °F | 64.9 °F | 4.07 in. |
| March | 55.1 °F | 70.4 °F | 4.24 in. |
| April | 61.9 °F | 76.5 °F | 4.44 in. |
| May | 69.5 °F | 82.2 °F | 5.25 in. |
| June | 74.8 °F | 88.7 °F | 7.23 in. |
| July | 76.9 °F | 89.1 °F | 8.83 in. |
| August | 77.0 °F | 89.3 °F | 8.41 in. |
| September | 74.5 °F | 86.1 °F | 6.19 in. |
| October | 66.5 °F | 79.5 °F | 4.46 in. |
| November | 56.2 °F | 70.7 °F | 4.13 in. |
| December | 49.0 °F | 64.0 °F | 3.81 in. |
| Annual | 63.1 °F | 76.9 °F | 66.24 in. |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |