| 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 |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 62561 - Riverton, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 22 | 32 | 42 | 52 | 62 | 66 | 63 | 55 | 44 | 33 | 22 | 42 |
| Avg Max Temp (°F) | 33 | 39 | 51 | 64 | 75 | 83 | 87 | 85 | 79 | 67 | 51 | 38 | 63 |
| Avg Precip (In.) | 1.65 | 1.83 | 3.13 | 3.55 | 4.18 | 3.82 | 3.73 | 3.51 | 2.95 | 2.71 | 2.97 | 2.58 | 36.63 |