Port Lavaca, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 16.8 °C (low) to 26.1 °C (high). Annual precipitation averages 1097.8 Millimeters. Port Lavaca is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.1 °C | 17.8 °C | 77.22 mm |
| February | 9.4 °C | 19.4 °C | 53.59 mm |
| March | 13.1 °C | 22.3 °C | 75.18 mm |
| April | 16.5 °C | 25.6 °C | 71.63 mm |
| May | 20.8 °C | 28.9 °C | 106.68 mm |
| June | 23.9 °C | 31.8 °C | 128.78 mm |
| July | 24.7 °C | 33 °C | 94.74 mm |
| August | 24.6 °C | 33.6 °C | 79.25 mm |
| September | 22.3 °C | 31.6 °C | 138.43 mm |
| October | 17.8 °C | 27.9 °C | 115.32 mm |
| November | 12.4 °C | 22.6 °C | 85.09 mm |
| December | 8.5 °C | 18.7 °C | 71.88 mm |
| Annual | 16.8 °C | 26.1 °C | 1097.79 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 |