Iron River, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 28.5 °F (low) to 50.9 °F (high). Annual precipitation averages 30.8 Inches. Iron River is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around Jun. 1 - Jun. 10 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.6 °F | 21.7 °F | 1.18 in. |
| February | 2.7 °F | 26.1 °F | 1.01 in. |
| March | 12.1 °F | 37.4 °F | 1.44 in. |
| April | 25.8 °F | 49.8 °F | 2.61 in. |
| May | 38.8 °F | 64.3 °F | 3.2 in. |
| June | 48.6 °F | 73.4 °F | 3.96 in. |
| July | 52.7 °F | 77.3 °F | 4.07 in. |
| August | 50.6 °F | 75.4 °F | 3.13 in. |
| September | 43.4 °F | 67.4 °F | 3.57 in. |
| October | 32.5 °F | 53.3 °F | 3.3 in. |
| November | 22.0 °F | 38.2 °F | 1.83 in. |
| December | 10.0 °F | 26.5 °F | 1.49 in. |
| Annual | 28.5 °F | 50.9 °F | 30.79 in. |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | Jun. 1 - Jun. 10 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |