Smithville, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.9 °C (low) to 26.8 °C (high). Annual precipitation averages 970.3 Millimeters. Smithville is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4 °C | 16.9 °C | 73.66 mm |
| February | 6.1 °C | 18.8 °C | 58.17 mm |
| March | 9.8 °C | 22.7 °C | 75.44 mm |
| April | 13.6 °C | 26.7 °C | 85.34 mm |
| May | 18.4 °C | 30.2 °C | 123.7 mm |
| June | 21.9 °C | 33.7 °C | 80.52 mm |
| July | 22.9 °C | 35.6 °C | 50.29 mm |
| August | 22.8 °C | 36.3 °C | 72.39 mm |
| September | 19.8 °C | 32.9 °C | 85.09 mm |
| October | 14.3 °C | 28.2 °C | 112.01 mm |
| November | 8.8 °C | 22.1 °C | 75.95 mm |
| December | 4.8 °C | 17.8 °C | 77.72 mm |
| Annual | 13.9 °C | 26.8 °C | 970.28 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |