Winthrop, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.9 °F (low) to 54.2 °F (high). Annual precipitation averages 30.7 Inches. Winthrop is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.8 °F | 21.8 °F | 0.81 in. |
| February | 8.5 °F | 26.7 °F | 0.84 in. |
| March | 21.2 °F | 39.0 °F | 1.57 in. |
| April | 34.3 °F | 55.0 °F | 2.75 in. |
| May | 47.0 °F | 68.2 °F | 4.05 in. |
| June | 58.0 °F | 78.3 °F | 5.05 in. |
| July | 61.6 °F | 82.2 °F | 3.69 in. |
| August | 59.0 °F | 79.7 °F | 3.9 in. |
| September | 50.3 °F | 72.8 °F | 3.11 in. |
| October | 37.3 °F | 58.2 °F | 2.41 in. |
| November | 24.4 °F | 41.4 °F | 1.46 in. |
| December | 11.9 °F | 27.4 °F | 1.08 in. |
| Annual | 34.9 °F | 54.2 °F | 30.72 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |