Ironton, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.5 °F (low) to 67.3 °F (high). Annual precipitation averages 46.8 Inches. Ironton is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.9 °F | 42.8 °F | 2.62 in. |
| February | 26.0 °F | 48.3 °F | 2.72 in. |
| March | 34.0 °F | 58.0 °F | 3.91 in. |
| April | 43.8 °F | 69.3 °F | 5.74 in. |
| May | 53.7 °F | 76.5 °F | 5.6 in. |
| June | 61.8 °F | 84.0 °F | 4.07 in. |
| July | 66.1 °F | 87.8 °F | 3.74 in. |
| August | 64.1 °F | 87.3 °F | 3.81 in. |
| September | 56.2 °F | 80.7 °F | 3.58 in. |
| October | 44.7 °F | 70.1 °F | 3.33 in. |
| November | 34.3 °F | 56.5 °F | 4.61 in. |
| December | 26.8 °F | 45.8 °F | 3.11 in. |
| Annual | 44.5 °F | 67.3 °F | 46.84 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |