Frost dates in Grand Coulee, WA
The average last spring frost in Grand Coulee is around April 21 and the first fall frost is around October 21. That gives Grand Coulee an average growing season of about 183 days.
Last spring frost
| Early (10% chance after) | April 2 |
|---|---|
| Average (50%) | April 21 |
| Late (90%) | May 8 |
First fall frost
| Early (10%) | October 10 |
|---|---|
| Average (50%) | October 21 |
| Late (90% chance before) | November 5 |