Frost dates in Boulder, UT
The average last spring frost in Boulder is around May 15 and the first fall frost is around October 5. That gives Boulder an average growing season of about 143 days.
Last spring frost
| Early (10% chance after) | April 28 |
|---|---|
| Average (50%) | May 15 |
| Late (90%) | June 1 |
First fall frost
| Early (10%) | September 19 |
|---|---|
| Average (50%) | October 5 |
| Late (90% chance before) | October 24 |