| 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: | Apr. 21 - Apr. 30 |
| 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 60431 - Joliet, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 19 | 28 | 38 | 48 | 59 | 63 | 61 | 53 | 42 | 32 | 20 | 40 |
| Avg Max Temp (°F) | 30 | 36 | 47 | 60 | 72 | 82 | 85 | 83 | 77 | 65 | 49 | 36 | 60 |
| Avg Precip (In.) | 1.6 | 1.6 | 2.54 | 3.73 | 3.94 | 4.28 | 4.13 | 3.87 | 3.2 | 2.72 | 3.04 | 2.43 | 37.09 |