Hahnville, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 16.3 °C (low) to 25.7 °C (high). Annual precipitation averages 1666.2 Millimeters. Hahnville is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Frost Rare through the first frost around Frost Rare.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.1 °C | 16.9 °C | 141.73 mm |
| February | 8.9 °C | 19.1 °C | 112.27 mm |
| March | 12.3 °C | 22.5 °C | 115.06 mm |
| April | 15.8 °C | 25.6 °C | 127.25 mm |
| May | 20.1 °C | 29.3 °C | 145.54 mm |
| June | 23.3 °C | 31.8 °C | 189.99 mm |
| July | 24.3 °C | 32.8 °C | 187.71 mm |
| August | 24.1 °C | 32.9 °C | 175.51 mm |
| September | 22.4 °C | 30.9 °C | 138.68 mm |
| October | 17.2 °C | 26.8 °C | 102.11 mm |
| November | 11.7 °C | 21.7 °C | 103.63 mm |
| December | 8.4 °C | 18.2 °C | 126.75 mm |
| Annual | 16.3 °C | 25.7 °C | 1666.23 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | Frost Rare |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |