Grand Mound, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.7 °F (low) to 59.2 °F (high). Annual precipitation averages 38.5 Inches. Grand Mound 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 | 12.9 °F | 29.3 °F | 1.32 in. |
| February | 16.6 °F | 33.7 °F | 1.59 in. |
| March | 27.5 °F | 46.7 °F | 2.42 in. |
| April | 38.6 °F | 60.4 °F | 3.83 in. |
| May | 50.5 °F | 71.6 °F | 4.75 in. |
| June | 60.6 °F | 80.8 °F | 4.89 in. |
| July | 64.0 °F | 83.8 °F | 4.32 in. |
| August | 61.8 °F | 81.9 °F | 4.49 in. |
| September | 53.4 °F | 76.2 °F | 3.86 in. |
| October | 41.6 °F | 63.2 °F | 3.0 in. |
| November | 29.7 °F | 48.0 °F | 2.18 in. |
| December | 19.3 °F | 34.8 °F | 1.81 in. |
| Annual | 39.7 °F | 59.2 °F | 38.46 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 |