| 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: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 54a - Illinois/Indiana Prairies |
| Heat Zone Days: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 61360 - Seneca, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 12 | 18 | 28 | 38 | 49 | 59 | 63 | 60 | 52 | 41 | 30 | 19 | 39 |
| Avg Max Temp (°F) | 30 | 35 | 47 | 61 | 73 | 82 | 85 | 83 | 76 | 64 | 48 | 35 | 60 |
| Avg Precip (In.) | 1.64 | 1.55 | 2.72 | 3.59 | 4.11 | 4.18 | 3.87 | 3.64 | 3.32 | 2.69 | 3.07 | 2.39 | 36.77 |