Chalmette, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 61.9 °F (low) to 78.5 °F (high). Annual precipitation averages 65.8 Inches. Chalmette is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 44.9 °F | 62.2 °F | 5.47 in. |
| February | 48.3 °F | 66.1 °F | 4.25 in. |
| March | 54.5 °F | 72.3 °F | 4.38 in. |
| April | 61.1 °F | 78.5 °F | 5.1 in. |
| May | 68.7 °F | 85.6 °F | 5.48 in. |
| June | 74.4 °F | 90.2 °F | 6.69 in. |
| July | 76.2 °F | 91.7 °F | 7.44 in. |
| August | 76.2 °F | 91.5 °F | 8.54 in. |
| September | 73.1 °F | 88.1 °F | 5.45 in. |
| October | 63.8 °F | 80.5 °F | 4.09 in. |
| November | 53.7 °F | 71.0 °F | 4.01 in. |
| December | 47.5 °F | 64.5 °F | 4.91 in. |
| Annual | 61.9 °F | 78.5 °F | 65.81 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 |