Sundown, Texas has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 7.1 °C (low) to 23.6 °C (high). Annual precipitation averages 450.6 Millimeters. Sundown is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.9 °C | 12.6 °C | 15.75 mm |
| February | -2.3 °C | 15.2 °C | 14.48 mm |
| March | 1.7 °C | 19.6 °C | 27.43 mm |
| April | 5.8 °C | 24 °C | 25.15 mm |
| May | 11.7 °C | 28.6 °C | 55.37 mm |
| June | 16.9 °C | 32.9 °C | 62.48 mm |
| July | 18.7 °C | 33.6 °C | 54.36 mm |
| August | 17.8 °C | 32.8 °C | 55.12 mm |
| September | 13.9 °C | 28.9 °C | 62.48 mm |
| October | 7.4 °C | 24.1 °C | 38.35 mm |
| November | 0.8 °C | 17.6 °C | 21.34 mm |
| December | -3.2 °C | 13.1 °C | 18.29 mm |
| Annual | 7.1 °C | 23.6 °C | 450.6 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |