Red Oak, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.2 °C (low) to 16.4 °C (high). Annual precipitation averages 913.1 Millimeters. Red Oak 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.7 °C | 0.1 °C | 21.84 mm |
| February | -8.4 °C | 2.9 °C | 28.7 mm |
| March | -2.3 °C | 10.2 °C | 51.31 mm |
| April | 3.4 °C | 17.1 °C | 87.12 mm |
| May | 10.4 °C | 22.9 °C | 147.83 mm |
| June | 16.3 °C | 28 °C | 140.97 mm |
| July | 18.3 °C | 29.9 °C | 91.19 mm |
| August | 16.8 °C | 29 °C | 98.81 mm |
| September | 11.6 °C | 25.6 °C | 85.09 mm |
| October | 4.7 °C | 18.8 °C | 77.72 mm |
| November | -2.2 °C | 9.8 °C | 48.26 mm |
| December | -7.7 °C | 2.8 °C | 34.29 mm |
| Annual | 4.2 °C | 16.4 °C | 913.13 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |