Koontz Lake, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 15.3 °C (high). Annual precipitation averages 1028.2 Millimeters. Koontz Lake is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.7 °C | -0.1 °C | 65.53 mm |
| February | -7.2 °C | 2.1 °C | 58.42 mm |
| March | -2.4 °C | 8.3 °C | 60.45 mm |
| April | 3.3 °C | 15.4 °C | 91.69 mm |
| May | 9.7 °C | 21.6 °C | 111.51 mm |
| June | 15.2 °C | 26.7 °C | 111.76 mm |
| July | 16.7 °C | 28.3 °C | 111.25 mm |
| August | 15.7 °C | 27.4 °C | 106.43 mm |
| September | 11.4 °C | 24.3 °C | 85.6 mm |
| October | 5.3 °C | 17.4 °C | 87.63 mm |
| November | -0.2 °C | 9.3 °C | 75.95 mm |
| December | -5.2 °C | 2.8 °C | 61.98 mm |
| Annual | 4.5 °C | 15.3 °C | 1028.2 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |