| 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: | 54a - Illinois/Indiana Prairies |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 60548 - Sandwich, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 11 | 17 | 27 | 37 | 48 | 58 | 63 | 61 | 52 | 40 | 30 | 18 | 39 |
| Avg Max Temp (°F) | 29 | 34 | 46 | 60 | 72 | 81 | 84 | 82 | 75 | 64 | 47 | 34 | 59 |
| Avg Precip (In.) | 1.62 | 1.49 | 2.6 | 3.65 | 4.09 | 4.32 | 3.96 | 3.97 | 3.41 | 2.69 | 3.05 | 2.31 | 37.15 |