Frost dates in Grantsburg, WI
The average last spring frost in Grantsburg is around May 12 and the first fall frost is around September 25. That gives Grantsburg an average growing season of about 136 days.
Last spring frost
| Early (10% chance after) | April 27 |
|---|---|
| Average (50%) | May 12 |
| Late (90%) | June 3 |
First fall frost
| Early (10%) | September 13 |
|---|---|
| Average (50%) | September 25 |
| Late (90% chance before) | October 13 |