Middletown, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42 °F (low) to 61.3 °F (high). Annual precipitation averages 39.2 Inches. Middletown is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.8 °F | 32.2 °F | 1.67 in. |
| February | 19.6 °F | 37.0 °F | 1.86 in. |
| March | 29.8 °F | 49.6 °F | 2.61 in. |
| April | 40.9 °F | 62.4 °F | 3.86 in. |
| May | 52.8 °F | 72.9 °F | 5.18 in. |
| June | 62.3 °F | 82.2 °F | 4.79 in. |
| July | 65.9 °F | 85.5 °F | 4.21 in. |
| August | 63.8 °F | 83.9 °F | 3.8 in. |
| September | 55.4 °F | 77.8 °F | 3.67 in. |
| October | 43.6 °F | 65.1 °F | 3.03 in. |
| November | 31.8 °F | 49.9 °F | 2.55 in. |
| December | 21.8 °F | 37.5 °F | 1.94 in. |
| Annual | 42 °F | 61.3 °F | 39.17 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |