Frost dates in Sullivan, IL
The average last spring frost in Sullivan is around April 16 and the first fall frost is around October 20. That gives Sullivan an average growing season of about 187 days.
Last spring frost
| Early (10% chance after) | April 8 |
|---|---|
| Average (50%) | April 16 |
| Late (90%) | April 29 |
First fall frost
| Early (10%) | October 6 |
|---|---|
| Average (50%) | October 20 |
| Late (90% chance before) | October 31 |