Flagstaff, AZ Frost Dates
The last spring frost in Flagstaff usually comes around June 4 and the first fall frost around September 28.
| Spring (last) | Fall (first) | |
|---|---|---|
| Frost, 32°F | June 4 | September 28 |
| Hard freeze, 28°F | May 20 | October 9 |
Growing season: about 115 days.
Frequently asked questions
When is the last frost in Flagstaff, AZ?
The median date of the last spring frost (32°F) is June 4. In half of years the last frost comes earlier and in half it comes later, so waiting a week or two past June 4 lowers the risk for tender plants.
When is the first frost in Flagstaff?
The median date of the first fall frost (32°F) is September 28, and a hard freeze (28°F) usually follows around October 9.
How long is the growing season in Flagstaff?
About 115 days between the median last spring frost and first fall frost.
NOAA NCEI U.S. Climate Normals 1991-2020, station USW00003103. Median (50% probability) dates. Low spots and valleys can frost later in spring and earlier in fall than the station.