Frost dates in Harper, IA
The average last spring frost in Harper is around April 23 and the first fall frost is around October 12. That gives Harper an average growing season of about 172 days.
Last spring frost
| Early (10% chance after) | April 8 |
|---|---|
| Average (50%) | April 23 |
| Late (90%) | May 7 |
First fall frost
| Early (10%) | September 27 |
|---|---|
| Average (50%) | October 12 |
| Late (90% chance before) | October 29 |