Iatan, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.1 °C (low) to 18.1 °C (high). Annual precipitation averages 977.1 Millimeters. 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 | -8.1 °C | 2.8 °C | 26.16 mm |
| February | -5.8 °C | 5.8 °C | 35.31 mm |
| March | -0.1 °C | 12.6 °C | 57.15 mm |
| April | 5.7 °C | 18.4 °C | 96.01 mm |
| May | 12.1 °C | 23.7 °C | 132.84 mm |
| June | 17.6 °C | 28.9 °C | 130.05 mm |
| July | 19.6 °C | 31.2 °C | 119.89 mm |
| August | 18.4 °C | 30.5 °C | 107.7 mm |
| September | 13.5 °C | 26.5 °C | 98.04 mm |
| October | 6.3 °C | 19.7 °C | 83.82 mm |
| November | -0.1 °C | 12.1 °C | 51.05 mm |
| December | -5.5 °C | 5.3 °C | 39.12 mm |
| Annual | 6.1 °C | 18.1 °C | 977.14 mm |
| 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 : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |