Frost dates in Williamsburg, IA
The average last spring frost in Williamsburg is around April 29 and the first fall frost is around October 7. That gives Williamsburg an average growing season of about 161 days.
Last spring frost
| Early (10% chance after) | April 15 |
|---|---|
| Average (50%) | April 29 |
| Late (90%) | May 17 |
First fall frost
| Early (10%) | September 22 |
|---|---|
| Average (50%) | October 7 |
| Late (90% chance before) | October 23 |