West Harrison, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.6 °C (low) to 18.1 °C (high). Annual precipitation averages 1143.5 Millimeters. West Harrison is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.1 °C | 4.2 °C | 85.6 mm |
| February | -4.1 °C | 6.4 °C | 70.1 mm |
| March | 0.3 °C | 11.9 °C | 99.06 mm |
| April | 5.7 °C | 18.6 °C | 118.11 mm |
| May | 11.6 °C | 23.6 °C | 126.24 mm |
| June | 16.6 °C | 28.2 °C | 119.63 mm |
| July | 18.4 °C | 29.9 °C | 102.36 mm |
| August | 17.7 °C | 29.7 °C | 83.31 mm |
| September | 13 °C | 26.4 °C | 80.26 mm |
| October | 6.3 °C | 19.6 °C | 82.3 mm |
| November | 0.9 °C | 12.4 °C | 84.58 mm |
| December | -2.6 °C | 6.3 °C | 91.95 mm |
| Annual | 6.6 °C | 18.1 °C | 1143.5 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |