South Haven, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.2 °C (low) to 15.4 °C (high). Annual precipitation averages 1031 Millimeters. South Haven is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.9 °C | 0.3 °C | 62.48 mm |
| February | -6.4 °C | 2.4 °C | 55.37 mm |
| March | -1.8 °C | 8.3 °C | 60.45 mm |
| April | 3.8 °C | 15.2 °C | 92.96 mm |
| May | 9.7 °C | 21.3 °C | 104.9 mm |
| June | 15.2 °C | 26.5 °C | 117.35 mm |
| July | 17.7 °C | 28.4 °C | 109.22 mm |
| August | 16.9 °C | 27.6 °C | 107.19 mm |
| September | 12.7 °C | 24.4 °C | 89.15 mm |
| October | 6.5 °C | 17.7 °C | 101.09 mm |
| November | 0.8 °C | 9.8 °C | 72.14 mm |
| December | -4.6 °C | 3.1 °C | 58.67 mm |
| Annual | 5.2 °C | 15.4 °C | 1030.97 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |