Sun Valley, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.8 °C (low) to 23.6 °C (high). Annual precipitation averages 1205.2 Millimeters. Sun Valley is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.4 °C | 12.1 °C | 81.03 mm |
| February | 2.4 °C | 14.4 °C | 91.95 mm |
| March | 6.7 °C | 18.9 °C | 109.73 mm |
| April | 10.8 °C | 23.2 °C | 108.97 mm |
| May | 16.4 °C | 27.2 °C | 133.35 mm |
| June | 20.9 °C | 31.8 °C | 99.06 mm |
| July | 22.8 °C | 34.1 °C | 77.98 mm |
| August | 22.2 °C | 34.6 °C | 69.6 mm |
| September | 18.4 °C | 30.8 °C | 100.33 mm |
| October | 11.9 °C | 24.9 °C | 116.84 mm |
| November | 6.2 °C | 18.2 °C | 103.12 mm |
| December | 1.9 °C | 13.2 °C | 113.28 mm |
| Annual | 11.8 °C | 23.6 °C | 1205.24 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |