Mill Spring, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 45.6 °F (low) to 68.6 °F (high). Annual precipitation averages 48.3 Inches. Mill Spring is located in USDA Plant Hardiness Zone 7a. 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 | 23.7 °F | 44.1 °F | 3.2 in. |
| February | 26.5 °F | 49.3 °F | 3.28 in. |
| March | 35.0 °F | 58.9 °F | 4.16 in. |
| April | 45.1 °F | 70.4 °F | 5.7 in. |
| May | 54.8 °F | 78.0 °F | 5.17 in. |
| June | 63.7 °F | 86.3 °F | 3.8 in. |
| July | 67.7 °F | 89.8 °F | 4.03 in. |
| August | 65.9 °F | 89.0 °F | 3.44 in. |
| September | 57.6 °F | 82.0 °F | 3.75 in. |
| October | 45.1 °F | 71.0 °F | 3.5 in. |
| November | 34.7 °F | 58.0 °F | 4.52 in. |
| December | 27.1 °F | 46.8 °F | 3.74 in. |
| Annual | 45.6 °F | 68.6 °F | 48.29 in. |
| 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |