Red Oak, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.5 °F (low) to 61.6 °F (high). Annual precipitation averages 36 Inches. 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 | 12.8 °F | 32.2 °F | 0.86 in. |
| February | 16.8 °F | 37.3 °F | 1.13 in. |
| March | 27.8 °F | 50.4 °F | 2.02 in. |
| April | 38.2 °F | 62.8 °F | 3.43 in. |
| May | 50.7 °F | 73.2 °F | 5.82 in. |
| June | 61.3 °F | 82.4 °F | 5.55 in. |
| July | 65.0 °F | 85.8 °F | 3.59 in. |
| August | 62.2 °F | 84.2 °F | 3.89 in. |
| September | 52.8 °F | 78.1 °F | 3.35 in. |
| October | 40.5 °F | 65.8 °F | 3.06 in. |
| November | 28.0 °F | 49.7 °F | 1.9 in. |
| December | 18.2 °F | 37.0 °F | 1.35 in. |
| Annual | 39.5 °F | 61.6 °F | 35.95 in. |
| 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 : -15°F to -10°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 |