South Haven, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.1 °F (low) to 53.1 °F (high). Annual precipitation averages 29.7 Inches. South Haven is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.8 °F | 21.1 °F | 0.72 in. |
| February | 7.0 °F | 25.7 °F | 0.86 in. |
| March | 19.9 °F | 38.4 °F | 1.44 in. |
| April | 33.3 °F | 53.9 °F | 2.67 in. |
| May | 46.3 °F | 67.1 °F | 3.92 in. |
| June | 56.8 °F | 76.7 °F | 4.24 in. |
| July | 61.1 °F | 80.8 °F | 3.92 in. |
| August | 58.3 °F | 78.7 °F | 4.02 in. |
| September | 50.1 °F | 71.5 °F | 3.09 in. |
| October | 37.3 °F | 56.7 °F | 2.48 in. |
| November | 24.1 °F | 40.2 °F | 1.35 in. |
| December | 11.2 °F | 26.5 °F | 1.0 in. |
| Annual | 34.1 °F | 53.1 °F | 29.71 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |