Sinton, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 16.8 °C (low) to 27.5 °C (high). Annual precipitation averages 850.9 Millimeters. Sinton is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.7 °C | 19.1 °C | 43.43 mm |
| February | 9.8 °C | 21.2 °C | 43.18 mm |
| March | 13.4 °C | 24 °C | 63.5 mm |
| April | 16.8 °C | 27.3 °C | 47.24 mm |
| May | 20.9 °C | 30.2 °C | 77.47 mm |
| June | 23.7 °C | 33 °C | 87.63 mm |
| July | 24.3 °C | 33.9 °C | 82.3 mm |
| August | 24.3 °C | 34.8 °C | 65.79 mm |
| September | 22.2 °C | 32.6 °C | 151.64 mm |
| October | 17.6 °C | 29.1 °C | 92.71 mm |
| November | 12.5 °C | 24 °C | 51.31 mm |
| December | 8.7 °C | 20.2 °C | 44.7 mm |
| Annual | 16.8 °C | 27.5 °C | 850.9 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 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |