| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 39f - St. Francois Knobs and Basins |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 63650 - Ironton, MO | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 22 | 26 | 34 | 44 | 52 | 60 | 65 | 63 | 55 | 45 | 36 | 26 | 44 |
| Avg Max Temp (°F) | 43 | 50 | 60 | 71 | 77 | 84 | 89 | 88 | 81 | 71 | 57 | 46 | 68 |
| Avg Precip (In.) | 2.61 | 2.69 | 4.06 | 4.64 | 4.94 | 4.05 | 3.7 | 4.12 | 3.53 | 3.42 | 5.18 | 3.68 | 46.62 |