| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°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 61938 - Mattoon, IL | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 22 | 32 | 42 | 53 | 62 | 66 | 64 | 56 | 45 | 33 | 23 | 43 |
| Avg Max Temp (°F) | 34 | 39 | 51 | 63 | 74 | 83 | 86 | 85 | 78 | 66 | 51 | 38 | 62 |
| Avg Precip (In.) | 2.06 | 2.11 | 3.18 | 3.84 | 4.07 | 4.11 | 4.23 | 3.31 | 3.05 | 3.01 | 3.7 | 2.94 | 39.63 |