Mehlville, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47.6 °F (low) to 66.8 °F (high). Annual precipitation averages 44.9 Inches. Mehlville is located in USDA Plant Hardiness Zone 7a. 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 | 24.0 °F | 40.7 °F | 2.77 in. |
| February | 27.4 °F | 46.0 °F | 2.5 in. |
| March | 36.0 °F | 56.1 °F | 3.63 in. |
| April | 46.7 °F | 68.3 °F | 4.73 in. |
| May | 57.3 °F | 77.0 °F | 5.3 in. |
| June | 66.1 °F | 85.5 °F | 4.65 in. |
| July | 70.1 °F | 89.1 °F | 4.17 in. |
| August | 68.0 °F | 87.7 °F | 3.77 in. |
| September | 60.1 °F | 81.2 °F | 3.38 in. |
| October | 48.9 °F | 69.5 °F | 3.51 in. |
| November | 37.3 °F | 55.4 °F | 3.7 in. |
| December | 28.8 °F | 44.8 °F | 2.81 in. |
| Annual | 47.6 °F | 66.8 °F | 44.92 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 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |