San Patricio, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 16.9 °C (low) to 27.9 °C (high). Annual precipitation averages 742.2 Millimeters. San Patricio is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.8 °C | 19.3 °C | 37.59 mm |
| February | 10 °C | 21.6 °C | 35.81 mm |
| March | 13.6 °C | 24.3 °C | 56.39 mm |
| April | 16.9 °C | 28 °C | 46.48 mm |
| May | 21 °C | 30.8 °C | 78.23 mm |
| June | 23.6 °C | 33.7 °C | 81.79 mm |
| July | 24.1 °C | 34.8 °C | 75.95 mm |
| August | 24.2 °C | 35.6 °C | 61.21 mm |
| September | 22.3 °C | 32.8 °C | 115.06 mm |
| October | 17.8 °C | 29.5 °C | 66.04 mm |
| November | 12.7 °C | 24.2 °C | 43.18 mm |
| December | 8.8 °C | 20.4 °C | 44.45 mm |
| Annual | 16.9 °C | 27.9 °C | 742.18 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 |