Colfax, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.7 °F (low) to 59.8 °F (high). Annual precipitation averages 36.4 Inches. Colfax is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.5 °F | 29.9 °F | 0.97 in. |
| February | 16.3 °F | 34.5 °F | 1.22 in. |
| March | 27.3 °F | 47.6 °F | 2.05 in. |
| April | 38.7 °F | 61.4 °F | 3.8 in. |
| May | 50.9 °F | 71.4 °F | 5.01 in. |
| June | 61.3 °F | 81.2 °F | 5.29 in. |
| July | 64.8 °F | 84.8 °F | 4.3 in. |
| August | 62.3 °F | 83.1 °F | 4.3 in. |
| September | 53.6 °F | 76.8 °F | 3.52 in. |
| October | 41.3 °F | 63.6 °F | 2.63 in. |
| November | 29.1 °F | 48.3 °F | 1.9 in. |
| December | 18.4 °F | 35.2 °F | 1.37 in. |
| Annual | 39.7 °F | 59.8 °F | 36.36 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |