Onward, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.4 °C (low) to 15.8 °C (high). Annual precipitation averages 1036.6 Millimeters. Onward 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.7 °C | 0.6 °C | 67.06 mm |
| February | -6.3 °C | 2.6 °C | 54.86 mm |
| March | -1.4 °C | 8.9 °C | 72.39 mm |
| April | 4.4 °C | 16.1 °C | 96.01 mm |
| May | 10.8 °C | 22.2 °C | 113.54 mm |
| June | 16.1 °C | 27.1 °C | 125.22 mm |
| July | 17.7 °C | 28.7 °C | 110.49 mm |
| August | 16.6 °C | 27.8 °C | 99.06 mm |
| September | 12.3 °C | 25 °C | 80.26 mm |
| October | 6.1 °C | 17.9 °C | 75.44 mm |
| November | 0.5 °C | 9.9 °C | 79.76 mm |
| December | -4.4 °C | 3.3 °C | 62.48 mm |
| Annual | 5.4 °C | 15.8 °C | 1036.57 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 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 |