Robstown, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 17.1 °C (low) to 27.8 °C (high). Annual precipitation averages 763.8 Millimeters. Robstown is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.9 °C | 19.4 °C | 37.34 mm |
| February | 10.2 °C | 21.8 °C | 37.34 mm |
| March | 13.8 °C | 24.7 °C | 53.59 mm |
| April | 17.2 °C | 27.8 °C | 43.18 mm |
| May | 21.2 °C | 30.6 °C | 76.2 mm |
| June | 23.7 °C | 33.3 °C | 78.49 mm |
| July | 24.3 °C | 34.4 °C | 66.55 mm |
| August | 24.3 °C | 35.1 °C | 68.83 mm |
| September | 22.5 °C | 32.7 °C | 130.05 mm |
| October | 18 °C | 29.4 °C | 81.53 mm |
| November | 12.9 °C | 24.3 °C | 48.51 mm |
| December | 9.1 °C | 20.6 °C | 42.16 mm |
| Annual | 17.1 °C | 27.8 °C | 763.77 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 |