| 2023 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 54f - Valparaiso-Wheaton Morainal Complex |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 60175 - Saint Charles, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 12 | 17 | 27 | 37 | 47 | 57 | 62 | 60 | 51 | 40 | 30 | 18 | 38 |
| Avg Max Temp (°F) | 28 | 34 | 46 | 59 | 71 | 80 | 84 | 82 | 75 | 63 | 47 | 34 | 58 |
| Avg Precip (In.) | 1.68 | 1.43 | 2.34 | 3.78 | 3.84 | 4.37 | 4 | 4.4 | 3.54 | 2.64 | 3.08 | 2.17 | 37.27 |