Jefferson, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 62.4 °F (low) to 78.3 °F (high). Annual precipitation averages 65.8 Inches. Jefferson is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 45.3 °F | 62.0 °F | 5.55 in. |
| February | 48.6 °F | 65.7 °F | 4.28 in. |
| March | 55.0 °F | 72.0 °F | 4.53 in. |
| April | 61.7 °F | 78.4 °F | 4.81 in. |
| May | 69.3 °F | 85.3 °F | 5.46 in. |
| June | 74.9 °F | 90.1 °F | 7.38 in. |
| July | 76.8 °F | 91.5 °F | 7.61 in. |
| August | 76.6 °F | 91.3 °F | 7.41 in. |
| September | 73.5 °F | 87.7 °F | 5.56 in. |
| October | 64.5 °F | 80.3 °F | 3.83 in. |
| November | 54.3 °F | 70.6 °F | 4.13 in. |
| December | 48.0 °F | 64.3 °F | 5.21 in. |
| Annual | 62.4 °F | 78.3 °F | 65.76 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 | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |