Iatan, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43 °F (low) to 64.6 °F (high). Annual precipitation averages 38.5 Inches. Iatan 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.4 °F | 37.1 °F | 1.03 in. |
| February | 21.5 °F | 42.5 °F | 1.39 in. |
| March | 31.8 °F | 54.6 °F | 2.25 in. |
| April | 42.2 °F | 65.1 °F | 3.78 in. |
| May | 53.7 °F | 74.6 °F | 5.23 in. |
| June | 63.7 °F | 84.0 °F | 5.12 in. |
| July | 67.3 °F | 88.1 °F | 4.72 in. |
| August | 65.1 °F | 86.9 °F | 4.24 in. |
| September | 56.3 °F | 79.7 °F | 3.86 in. |
| October | 43.4 °F | 67.5 °F | 3.3 in. |
| November | 31.9 °F | 53.7 °F | 2.01 in. |
| December | 22.1 °F | 41.5 °F | 1.54 in. |
| Annual | 43 °F | 64.6 °F | 38.47 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |