Port Allen, Louisiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 14.2 °C (low) to 25.8 °C (high). Annual precipitation averages 1645.9 Millimeters. Port Allen is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.9 °C | 16.6 °C | 159.51 mm |
| February | 6.8 °C | 18.8 °C | 125.73 mm |
| March | 10.2 °C | 22.6 °C | 116.59 mm |
| April | 13.6 °C | 26 °C | 134.11 mm |
| May | 18.2 °C | 29.7 °C | 147.32 mm |
| June | 21.7 °C | 32.2 °C | 171.96 mm |
| July | 22.9 °C | 33 °C | 149.86 mm |
| August | 22.6 °C | 33.3 °C | 165.86 mm |
| September | 20.2 °C | 31.3 °C | 117.09 mm |
| October | 14.2 °C | 27.1 °C | 118.62 mm |
| November | 8.7 °C | 21.4 °C | 105.16 mm |
| December | 5.9 °C | 17.7 °C | 134.11 mm |
| Annual | 14.2 °C | 25.8 °C | 1645.92 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |