Smithville, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.3 °C (low) to 18.1 °C (high). Annual precipitation averages 1019.3 Millimeters. Smithville is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.7 °C | 3.3 °C | 29.72 mm |
| February | -5.5 °C | 6.3 °C | 38.35 mm |
| March | 0 °C | 12.6 °C | 55.88 mm |
| April | 5.7 °C | 18.3 °C | 98.04 mm |
| May | 11.9 °C | 23.5 °C | 138.94 mm |
| June | 17.4 °C | 28.7 °C | 135.13 mm |
| July | 19.8 °C | 31.1 °C | 123.95 mm |
| August | 18.4 °C | 30.4 °C | 111.25 mm |
| September | 13.4 °C | 26.2 °C | 108.71 mm |
| October | 6.7 °C | 19.7 °C | 86.61 mm |
| November | 0.2 °C | 12 °C | 52.32 mm |
| December | -5.1 °C | 5.6 °C | 40.39 mm |
| Annual | 6.3 °C | 18.1 °C | 1019.29 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |