Iron River, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.9 °F (low) to 51.5 °F (high). Annual precipitation averages 32.9 Inches. Iron River is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.2 °F | 20.7 °F | 1.18 in. |
| February | 4.1 °F | 26.2 °F | 1.05 in. |
| March | 15.7 °F | 38.0 °F | 1.71 in. |
| April | 28.1 °F | 50.9 °F | 2.79 in. |
| May | 39.6 °F | 65.0 °F | 3.5 in. |
| June | 49.6 °F | 73.9 °F | 4.11 in. |
| July | 55.2 °F | 78.7 °F | 4.31 in. |
| August | 53.5 °F | 76.8 °F | 3.81 in. |
| September | 45.9 °F | 68.7 °F | 3.5 in. |
| October | 34.2 °F | 54.4 °F | 3.23 in. |
| November | 22.6 °F | 38.9 °F | 2.08 in. |
| December | 9.6 °F | 25.9 °F | 1.64 in. |
| Annual | 29.9 °F | 51.5 °F | 32.91 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |