Boswell, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 16.2 °C (high). Annual precipitation averages 1005.3 Millimeters. Boswell 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 | -8.3 °C | 0.3 °C | 56.13 mm |
| February | -6.7 °C | 2.8 °C | 47.5 mm |
| March | -1.6 °C | 9.3 °C | 69.09 mm |
| April | 4.2 °C | 16.9 °C | 102.11 mm |
| May | 10.7 °C | 22.9 °C | 111.76 mm |
| June | 15.9 °C | 27.6 °C | 128.02 mm |
| July | 17.4 °C | 28.8 °C | 114.55 mm |
| August | 16.2 °C | 28.1 °C | 86.61 mm |
| September | 11.9 °C | 25.6 °C | 77.98 mm |
| October | 5.7 °C | 18.6 °C | 82.04 mm |
| November | -0.1 °C | 10.1 °C | 71.88 mm |
| December | -5.2 °C | 3.2 °C | 57.66 mm |
| Annual | 5 °C | 16.2 °C | 1005.33 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 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 |