Onaway, Idaho has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 2.2 °C (low) to 14.5 °C (high). Annual precipitation averages 605.3 Millimeters. Onaway is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.6 °C | 2.7 °C | 71.37 mm |
| February | -3.2 °C | 4.8 °C | 56.39 mm |
| March | -1.2 °C | 8.9 °C | 60.96 mm |
| April | 1.4 °C | 13.3 °C | 55.37 mm |
| May | 4.8 °C | 18.6 °C | 60.2 mm |
| June | 7.4 °C | 21.7 °C | 43.94 mm |
| July | 9.4 °C | 28.1 °C | 18.54 mm |
| August | 9.2 °C | 28.8 °C | 16.26 mm |
| September | 5.8 °C | 23.4 °C | 22.1 mm |
| October | 2 °C | 15.1 °C | 53.09 mm |
| November | -1.1 °C | 6.8 °C | 72.9 mm |
| December | -4.1 °C | 2 °C | 74.17 mm |
| Annual | 2.2 °C | 14.5 °C | 605.29 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 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 | Severe Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |