Millersburg, Iowa has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.8 °F (low) to 59.2 °F (high). Annual precipitation averages 37.5 Inches. Millersburg is located in USDA Plant Hardiness Zone 5b. 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 | 11.9 °F | 29.0 °F | 1.18 in. |
| February | 15.6 °F | 33.7 °F | 1.42 in. |
| March | 26.5 °F | 46.7 °F | 2.18 in. |
| April | 37.6 °F | 60.4 °F | 3.71 in. |
| May | 50.0 °F | 71.3 °F | 4.99 in. |
| June | 60.6 °F | 80.9 °F | 5.16 in. |
| July | 63.8 °F | 84.2 °F | 4.17 in. |
| August | 61.0 °F | 82.4 °F | 4.57 in. |
| September | 52.1 °F | 76.1 °F | 3.44 in. |
| October | 40.1 °F | 63.1 °F | 2.94 in. |
| November | 28.2 °F | 47.6 °F | 2.08 in. |
| December | 18.0 °F | 34.5 °F | 1.61 in. |
| Annual | 38.8 °F | 59.2 °F | 37.45 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 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 |