| 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: | 39d - Central Plateau |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 63077 - Saint Clair, MO | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 20 | 25 | 34 | 44 | 53 | 62 | 67 | 65 | 56 | 44 | 35 | 25 | 44 |
| Avg Max Temp (°F) | 40 | 47 | 58 | 69 | 77 | 85 | 90 | 88 | 81 | 70 | 56 | 44 | 67 |
| Avg Precip (In.) | 2.22 | 2.27 | 3.66 | 3.99 | 4.43 | 3.91 | 3.81 | 3.45 | 3.47 | 3.12 | 4.08 | 2.95 | 41.38 |