Chalmette, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 16.6 °C (low) to 25.9 °C (high). Annual precipitation averages 1671.6 Millimeters. Chalmette is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.2 °C | 16.8 °C | 138.94 mm |
| February | 9.1 °C | 18.9 °C | 107.95 mm |
| March | 12.5 °C | 22.4 °C | 111.25 mm |
| April | 16.2 °C | 25.8 °C | 129.54 mm |
| May | 20.4 °C | 29.8 °C | 139.19 mm |
| June | 23.6 °C | 32.3 °C | 169.93 mm |
| July | 24.6 °C | 33.2 °C | 188.98 mm |
| August | 24.6 °C | 33.1 °C | 216.92 mm |
| September | 22.8 °C | 31.2 °C | 138.43 mm |
| October | 17.7 °C | 26.9 °C | 103.89 mm |
| November | 12.1 °C | 21.7 °C | 101.85 mm |
| December | 8.6 °C | 18.1 °C | 124.71 mm |
| Annual | 16.6 °C | 25.9 °C | 1671.58 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |