Frost dates · USDA zone 6a
Frost dates for Flagstaff, AZ
Flagstaff, AZ sees its last 32 °F night of spring around June 4 and its first of fall around September 28 — a 115-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | May 21 | Oct 9 |
| Median — 1 year in 2 | Jun 4 | Sep 28 |
| 1 year in 10 | Jun 19 | Sep 16 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 115 days median, at least 96 in 9 years of 10, at least 133 days in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of May 20 and first of Oct 9.
Flagstaff planting calendar, 2027
Every row runs from the median last frost (Jun 4) and median first frost (Sep 28) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Mar 12 | May 7 | Aug 25 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Jun 4 | Jul 4 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | May 21 | May 21 | Jul 5 | 45 from sow |
| Genovese BasilGenovese | May 7 | Jun 18 | Aug 17 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Apr 9 | Jun 11 | Aug 25 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Mar 26 | Jun 18 | Sep 21 tight | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Apr 9 | Jun 11 | Aug 25 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Apr 9 | Jun 11 | Aug 30 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Apr 9 | Jun 11 | Aug 30 | 80 from transplant |
| Nantes CarrotScarlet Nantes | May 21 | May 21 | Jul 30 | 70 from sow |
| TomatilloToma Verde | Apr 23 | Jun 11 | Aug 20 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Apr 23 | Jun 11 | Aug 25 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Apr 23 | Jun 11 | Aug 30 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can Flagstaff grow?
Each sauce, scheduled for a Flagstaff container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Flagstaff frost questions
When is the last frost in Flagstaff, AZ?
The median last 32 °F freeze at FLAGSTAFF PULLIAM AP, AZ is June 4: half of years see a later one. One year in ten, a freeze still comes after June 19; nine years in ten, it comes after May 21. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Flagstaff, AZ?
The median first 32 °F freeze of fall is September 28. One year in ten it arrives before September 16; nine years in ten, before October 9.
How long is the growing season in Flagstaff, AZ?
115 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 96 days; one year in ten, at least 133 days.
What growing zone is Flagstaff, AZ?
USDA hardiness zone 6a, per the 2023 USDA Plant Hardiness Zone Map for ZIP 86005. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in Flagstaff, AZ?
Start Roma VF (determinate paste) seeds indoors around Apr 23 and transplant around Jun 11, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Jun 19. First ripe fruit lands around Aug 25.
When should I plant peppers in Flagstaff, AZ?
Sow jalapeño indoors on a heat mat around Apr 9; transplant no earlier than Jun 11, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Aug 25.
Nearby in Arizona
- Prescott Valleylast frost Apr 30
- Prescottlast frost Apr 30
- Peorialast frost Feb 5
- Scottsdalelast frost Jan 27
- Phoenixlast frost Jan 8
- Surpriselast frost Feb 5
All Arizona frost dates → · How frost-date math drives a sowing calendar →