| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 21 - Oct. 31 |
| 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: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 60515 - Downers Grove, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 19 | 28 | 38 | 48 | 57 | 63 | 61 | 53 | 42 | 31 | 20 | 39 |
| Avg Max Temp (°F) | 31 | 37 | 48 | 61 | 73 | 82 | 85 | 84 | 77 | 65 | 49 | 36 | 61 |
| Avg Precip (In.) | 1.8 | 1.55 | 2.61 | 3.76 | 3.91 | 4.04 | 3.95 | 4.46 | 3.39 | 2.67 | 3.15 | 2.43 | 37.7 |