Delmar, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.9 °F (low) to 57.9 °F (high). Annual precipitation averages 37.5 Inches. Delmar 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 | 11.0 °F | 27.8 °F | 1.37 in. |
| February | 14.6 °F | 32.3 °F | 1.61 in. |
| March | 25.8 °F | 45.4 °F | 2.31 in. |
| April | 36.7 °F | 59.0 °F | 3.71 in. |
| May | 48.7 °F | 70.4 °F | 4.45 in. |
| June | 58.9 °F | 79.7 °F | 5.07 in. |
| July | 62.2 °F | 82.6 °F | 4.27 in. |
| August | 59.9 °F | 80.9 °F | 4.19 in. |
| September | 51.4 °F | 74.9 °F | 3.64 in. |
| October | 39.6 °F | 61.9 °F | 2.96 in. |
| November | 27.9 °F | 46.5 °F | 2.14 in. |
| December | 17.5 °F | 33.5 °F | 1.78 in. |
| Annual | 37.9 °F | 57.9 °F | 37.5 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 |