| 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: | 72d - Upper Mississippi Alluvial Plain |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 61275 - Port Byron, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 18 | 29 | 40 | 52 | 61 | 66 | 63 | 55 | 43 | 31 | 19 | 41 |
| Avg Max Temp (°F) | 29 | 35 | 47 | 61 | 72 | 82 | 85 | 83 | 75 | 64 | 47 | 34 | 59 |
| Avg Precip (In.) | 1.25 | 1.33 | 2.43 | 3.36 | 3.95 | 4.57 | 3.71 | 4.41 | 3.05 | 2.61 | 2.48 | 2 | 35.16 |