Hepburn, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.3 °C (low) to 16.5 °C (high). Annual precipitation averages 913.6 Millimeters. Hepburn is located in USDA Plant Hardiness Zone 5b. 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 | -10.6 °C | 0.3 °C | 20.83 mm |
| February | -8.2 °C | 3.3 °C | 27.18 mm |
| March | -2.2 °C | 10.4 °C | 53.34 mm |
| April | 3.6 °C | 17.1 °C | 85.85 mm |
| May | 10.4 °C | 22.7 °C | 142.49 mm |
| June | 16.3 °C | 27.8 °C | 137.41 mm |
| July | 18.3 °C | 29.8 °C | 110.49 mm |
| August | 16.8 °C | 28.9 °C | 93.98 mm |
| September | 11.6 °C | 25.6 °C | 85.09 mm |
| October | 4.7 °C | 18.7 °C | 74.17 mm |
| November | -2 °C | 10.1 °C | 49.78 mm |
| December | -7.4 °C | 3.1 °C | 33.02 mm |
| Annual | 4.3 °C | 16.5 °C | 913.63 mm |
| 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 5b : -26.1°C to -23.3°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 |