| 2023 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | 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: | 72l - Karstic Northern Ozarkian River Bluffs |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 62233 - Chester, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 25 | 34 | 44 | 54 | 63 | 67 | 65 | 57 | 45 | 35 | 26 | 45 |
| Avg Max Temp (°F) | 39 | 46 | 56 | 67 | 77 | 86 | 90 | 88 | 81 | 70 | 56 | 44 | 67 |
| Avg Precip (In.) | 2.51 | 2.55 | 3.97 | 3.9 | 4.6 | 4.3 | 4.1 | 3.42 | 3.51 | 3.07 | 4.41 | 3.45 | 43.81 |