Smithville, Oklahoma has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 48.9 °F (low) to 73.1 °F (high). Annual precipitation averages 56.3 Inches. Smithville 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 | 28.8 °F | 52.7 °F | 3.92 in. |
| February | 32.1 °F | 56.9 °F | 3.8 in. |
| March | 39.5 °F | 64.8 °F | 4.94 in. |
| April | 47.2 °F | 72.9 °F | 5.47 in. |
| May | 57.3 °F | 79.3 °F | 6.96 in. |
| June | 65.4 °F | 87.3 °F | 4.34 in. |
| July | 68.8 °F | 91.5 °F | 3.97 in. |
| August | 67.5 °F | 92.8 °F | 3.54 in. |
| September | 60.8 °F | 86.1 °F | 4.44 in. |
| October | 48.9 °F | 75.0 °F | 5.43 in. |
| November | 39.2 °F | 63.7 °F | 4.58 in. |
| December | 31.7 °F | 54.5 °F | 4.87 in. |
| Annual | 48.9 °F | 73.1 °F | 56.26 in. |
| 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 : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7b : 5°F to 10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |