Ironton, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30.9 °F (low) to 51.2 °F (high). Annual precipitation averages 29.4 Inches. Ironton is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.3 °F | 18.9 °F | 0.8 in. |
| February | 2.5 °F | 24.5 °F | 0.83 in. |
| March | 15.9 °F | 37.5 °F | 1.45 in. |
| April | 30.2 °F | 51.6 °F | 2.31 in. |
| May | 43.5 °F | 65.0 °F | 3.46 in. |
| June | 53.9 °F | 74.7 °F | 4.36 in. |
| July | 57.9 °F | 79.4 °F | 4.5 in. |
| August | 55.2 °F | 77.2 °F | 3.58 in. |
| September | 46.8 °F | 68.8 °F | 2.97 in. |
| October | 34.7 °F | 54.1 °F | 2.8 in. |
| November | 22.0 °F | 37.9 °F | 1.39 in. |
| December | 8.9 °F | 24.6 °F | 0.97 in. |
| Annual | 30.9 °F | 51.2 °F | 29.42 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |