Frost dates for Flagstaff 4 SW, AZ
At Flagstaff 4 SW, the median last spring frost (32°F) is Jun 23 and the median first fall frost is Sep 15, for a typical growing season of 81 days. For a 90% chance that the last frost has passed, wait until Jul 7. Nearby ZIP codes are in USDA hardiness zones 5b to 8b.
- Jun 23Last spring frost (median)50% chance of 32°F after this date
- Jul 7Safer planting date10% chance of 32°F after this date
- Sep 15First fall frost (median)50% chance of 32°F by this date
- 81 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 32°F | Jun 10 | Jun 23 | Jul 7 |
| 28°F | May 29 | Jun 10 | Jun 26 |
| 24°F | May 10 | May 29 | Jun 10 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 32°F | Aug 31 | Sep 15 | Sep 27 |
| 28°F | Sep 11 | Sep 26 | Oct 7 |
| 24°F | Sep 23 | Oct 5 | Oct 19 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 38 days | 61 days | 79 days |
| 32°F | 59 days | 81 days | 100 days |
| 28°F | 83 days | 103 days | 123 days |
| 24°F | 109 days | 130 days | 152 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 86015 | 5b | -15 to -10°F | 10 km |
| 86005 | 6a | -10 to -5°F | 13 km |
| 86001 | 6a | -10 to -5°F | 22 km |
| 86018 | 6b | -5 to 0°F | 23 km |
| 86017 | 7a | 0 to 5°F | 25 km |
| 86336 | 8b | 15 to 20°F | 33 km |
| 86038 | 6b | -5 to 0°F | 36 km |
| 86004 | 6b | -5 to 0°F | 41 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00023009, at 35.1611, -111.7311, elevation 2172 m (7,125 ft).
- Data quality: Representative (10+ years), 21 years of freeze data.
- Average days per year at or below 32°F: 237.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Flagstaff Pulliam Airport (6 km)
- Bellemont WFO (11 km)
- Fort Valley (12 km)
- Walnut Canyon National Monument (20 km)
- Oak Creek Canyon (22 km)
- Mund's Park (26 km)
- Sunset Crater National Monument (29 km)
- Sedona (30 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.