| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| 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: | 39g - Meramec River Hills |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 63080 - Sullivan, MO | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 24 | 33 | 43 | 52 | 61 | 65 | 63 | 55 | 44 | 34 | 24 | 43 |
| Avg Max Temp (°F) | 40 | 47 | 58 | 69 | 77 | 84 | 89 | 88 | 80 | 70 | 56 | 45 | 67 |
| Avg Precip (In.) | 2.21 | 2.31 | 3.63 | 4.03 | 4.37 | 4 | 4.07 | 3.52 | 3.46 | 3.05 | 4.14 | 2.86 | 41.65 |