| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| 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: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 61856 - Monticello, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 16 | 20 | 31 | 41 | 51 | 61 | 64 | 62 | 54 | 43 | 32 | 22 | 41 |
| Avg Max Temp (°F) | 33 | 39 | 50 | 63 | 74 | 84 | 86 | 85 | 79 | 67 | 51 | 38 | 62 |
| Avg Precip (In.) | 2 | 1.92 | 3.14 | 3.76 | 4.35 | 4 | 4.5 | 4.12 | 2.86 | 2.75 | 3.34 | 2.82 | 39.57 |