Ionia, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.8 °F (low) to 65.1 °F (high). Annual precipitation averages 43.5 Inches. Ionia is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 19.6 °F | 39.3 °F | 1.84 in. |
| February | 23.4 °F | 44.3 °F | 2.11 in. |
| March | 32.7 °F | 55.0 °F | 2.93 in. |
| April | 42.7 °F | 65.6 °F | 4.64 in. |
| May | 53.4 °F | 74.2 °F | 5.15 in. |
| June | 62.8 °F | 83.1 °F | 5.25 in. |
| July | 67.0 °F | 87.6 °F | 4.32 in. |
| August | 65.0 °F | 86.8 °F | 4.01 in. |
| September | 56.8 °F | 79.5 °F | 4.52 in. |
| October | 44.6 °F | 67.8 °F | 3.56 in. |
| November | 33.6 °F | 54.8 °F | 3.0 in. |
| December | 24.1 °F | 43.3 °F | 2.17 in. |
| Annual | 43.8 °F | 65.1 °F | 43.5 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |