Glenwood, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40 °F (low) to 61.7 °F (high). Annual precipitation averages 33.5 Inches. Glenwood is located in USDA Plant Hardiness Zone 5b. 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 | 13.4 °F | 32.5 °F | 0.75 in. |
| February | 17.3 °F | 37.6 °F | 0.98 in. |
| March | 28.2 °F | 50.7 °F | 1.81 in. |
| April | 38.9 °F | 62.9 °F | 3.54 in. |
| May | 51.0 °F | 73.1 °F | 5.42 in. |
| June | 61.6 °F | 82.9 °F | 5.27 in. |
| July | 65.8 °F | 86.1 °F | 3.82 in. |
| August | 63.1 °F | 84.7 °F | 3.71 in. |
| September | 53.5 °F | 78.2 °F | 3.09 in. |
| October | 41.0 °F | 65.5 °F | 2.52 in. |
| November | 28.2 °F | 49.6 °F | 1.5 in. |
| December | 18.3 °F | 37.1 °F | 1.13 in. |
| Annual | 40 °F | 61.7 °F | 33.54 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |