Colfax, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 3.2 °C (low) to 15.8 °C (high). Annual precipitation averages 500.9 Millimeters. Colfax is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.8 °C | 3.7 °C | 65.79 mm |
| February | -2.2 °C | 6.2 °C | 50.04 mm |
| March | -0.1 °C | 10.4 °C | 55.88 mm |
| April | 2.3 °C | 14.8 °C | 44.7 mm |
| May | 5.7 °C | 19.9 °C | 42.42 mm |
| June | 8.4 °C | 23.2 °C | 31.24 mm |
| July | 10.7 °C | 29.5 °C | 11.68 mm |
| August | 10.5 °C | 29.9 °C | 10.67 mm |
| September | 7 °C | 24.7 °C | 12.7 mm |
| October | 2.8 °C | 16.3 °C | 37.59 mm |
| November | -0.3 °C | 8 °C | 64.01 mm |
| December | -3.3 °C | 3.1 °C | 74.17 mm |
| Annual | 3.2 °C | 15.8 °C | 500.89 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |