Washburn, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.8 °F (low) to 58 °F (high). Annual precipitation averages 38.5 Inches. Washburn is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 9.9 °F | 26.9 °F | 1.13 in. |
| February | 13.9 °F | 31.3 °F | 1.23 in. |
| March | 25.4 °F | 44.6 °F | 2.11 in. |
| April | 36.9 °F | 59.3 °F | 4.02 in. |
| May | 49.3 °F | 70.9 °F | 4.86 in. |
| June | 59.8 °F | 80.5 °F | 5.72 in. |
| July | 63.1 °F | 83.6 °F | 4.82 in. |
| August | 60.2 °F | 81.7 °F | 4.31 in. |
| September | 51.4 °F | 75.7 °F | 3.72 in. |
| October | 39.4 °F | 62.3 °F | 2.94 in. |
| November | 27.2 °F | 46.0 °F | 2.04 in. |
| December | 16.5 °F | 32.7 °F | 1.55 in. |
| Annual | 37.8 °F | 58 °F | 38.45 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |