Miller, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 35.8 °F (low) to 55.5 °F (high). Annual precipitation averages 34.4 Inches. Miller 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 | 7.0 °F | 23.8 °F | 0.93 in. |
| February | 11.2 °F | 28.6 °F | 0.96 in. |
| March | 23.5 °F | 41.1 °F | 1.97 in. |
| April | 35.0 °F | 56.5 °F | 3.74 in. |
| May | 47.5 °F | 68.9 °F | 4.86 in. |
| June | 58.3 °F | 78.8 °F | 5.34 in. |
| July | 61.5 °F | 81.8 °F | 4.36 in. |
| August | 58.7 °F | 79.6 °F | 3.86 in. |
| September | 49.9 °F | 73.5 °F | 3.2 in. |
| October | 37.5 °F | 60.2 °F | 2.33 in. |
| November | 25.4 °F | 43.4 °F | 1.58 in. |
| December | 13.9 °F | 29.7 °F | 1.29 in. |
| Annual | 35.8 °F | 55.5 °F | 34.42 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |