Three Rivers, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 15.8 °C (low) to 28.5 °C (high). Annual precipitation averages 672.4 Millimeters. Three Rivers is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 6.3 °C | 19.4 °C | 37.08 mm |
| February | 8.7 °C | 21.6 °C | 37.34 mm |
| March | 12.3 °C | 25.1 °C | 58.17 mm |
| April | 15.6 °C | 28.6 °C | 50.29 mm |
| May | 20.2 °C | 31.9 °C | 77.47 mm |
| June | 23.1 °C | 34.9 °C | 71.12 mm |
| July | 23.6 °C | 35.9 °C | 61.98 mm |
| August | 23.6 °C | 36.8 °C | 47.5 mm |
| September | 21.4 °C | 33.6 °C | 93.98 mm |
| October | 16.6 °C | 29.7 °C | 57.66 mm |
| November | 11.2 °C | 24.3 °C | 39.88 mm |
| December | 7.2 °C | 20.1 °C | 39.88 mm |
| Annual | 15.8 °C | 28.5 °C | 672.35 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |