| 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: | 54a - Illinois/Indiana Prairies | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 60112 - Cortland, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 15 | 26 | 37 | 48 | 58 | 62 | 60 | 51 | 40 | 28 | 17 | 38 |
| Avg Max Temp (°F) | 27 | 32 | 44 | 58 | 70 | 80 | 83 | 81 | 74 | 62 | 46 | 32 | 58 |
| Avg Precip (In.) | 1.55 | 1.39 | 2.43 | 3.57 | 4.09 | 4.5 | 4.18 | 4.39 | 3.48 | 2.64 | 2.89 | 2.12 | 37.22 |