Readlyn, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 36.7 °F (low) to 56.7 °F (high). Annual precipitation averages 37.9 Inches. Readlyn 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 | 8.6 °F | 25.7 °F | 1.09 in. |
| February | 12.6 °F | 29.8 °F | 1.13 in. |
| March | 24.4 °F | 43.2 °F | 1.99 in. |
| April | 35.9 °F | 57.9 °F | 3.93 in. |
| May | 48.1 °F | 69.9 °F | 4.96 in. |
| June | 58.9 °F | 79.6 °F | 5.92 in. |
| July | 62.0 °F | 82.5 °F | 4.69 in. |
| August | 59.3 °F | 80.5 °F | 4.17 in. |
| September | 50.8 °F | 74.5 °F | 3.7 in. |
| October | 38.5 °F | 61.1 °F | 2.85 in. |
| November | 26.3 °F | 44.8 °F | 1.94 in. |
| December | 15.3 °F | 31.4 °F | 1.57 in. |
| Annual | 36.7 °F | 56.7 °F | 37.94 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 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 |