Iron Mountain Lake, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.3 °C (low) to 19.2 °C (high). Annual precipitation averages 1192.5 Millimeters. Iron Mountain Lake 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 | -4.9 °C | 5.8 °C | 66.55 mm |
| February | -3.1 °C | 8.8 °C | 68.58 mm |
| March | 1.3 °C | 13.9 °C | 99.06 mm |
| April | 6.9 °C | 20.2 °C | 146.56 mm |
| May | 12.3 °C | 24.1 °C | 142.49 mm |
| June | 16.9 °C | 28.4 °C | 104.9 mm |
| July | 19.2 °C | 30.7 °C | 96.01 mm |
| August | 18.2 °C | 30.3 °C | 96.27 mm |
| September | 14.1 °C | 26.7 °C | 91.69 mm |
| October | 7.9 °C | 20.9 °C | 85.34 mm |
| November | 1.8 °C | 13.5 °C | 116.59 mm |
| December | -2.8 °C | 7.5 °C | 78.49 mm |
| Annual | 7.3 °C | 19.2 °C | 1192.53 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 6b : -20.6°C to -17.8°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 |