Mahtowa, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30 °F (low) to 51 °F (high). Annual precipitation averages 31.5 Inches. Mahtowa 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 | 0.5 °F | 19.8 °F | 0.85 in. |
| February | 4.0 °F | 25.5 °F | 0.88 in. |
| March | 16.0 °F | 37.4 °F | 1.39 in. |
| April | 28.5 °F | 50.4 °F | 2.48 in. |
| May | 39.5 °F | 64.3 °F | 3.52 in. |
| June | 49.2 °F | 73.5 °F | 4.56 in. |
| July | 55.5 °F | 78.9 °F | 4.48 in. |
| August | 54.1 °F | 77.1 °F | 3.9 in. |
| September | 46.3 °F | 68.6 °F | 3.39 in. |
| October | 34.8 °F | 53.9 °F | 3.09 in. |
| November | 22.2 °F | 38.0 °F | 1.66 in. |
| December | 8.8 °F | 24.8 °F | 1.31 in. |
| Annual | 30 °F | 51 °F | 31.51 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |