| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F 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: | 72f - River Hills | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 61571 - Washington, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 19 | 29 | 39 | 50 | 59 | 63 | 61 | 53 | 42 | 31 | 20 | 40 |
| Avg Max Temp (°F) | 31 | 37 | 49 | 63 | 74 | 83 | 86 | 84 | 78 | 66 | 49 | 36 | 61 |
| Avg Precip (In.) | 1.68 | 1.68 | 2.92 | 3.6 | 4.23 | 4.12 | 3.97 | 3.44 | 3.36 | 2.79 | 3.11 | 2.51 | 37.4 |