Frost dates for Superior, AZ
At Superior, the median last spring frost (32°F) is Jan 18 and the median first fall frost is Dec 28, for a typical growing season of 342 days. For a 90% chance that the last frost has passed, wait until Mar 1. Nearby ZIP codes are in USDA hardiness zone 9b.
- Jan 18Last spring frost (median)50% chance of 32°F after this date
- Mar 1Safer planting date10% chance of 32°F after this date
- Dec 28First fall frost (median)50% chance of 32°F by this date
- 342 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 |
|---|---|---|---|
| 36°F | Jan 8 | Feb 18 | Mar 31 |
| 32°F | Dec 19 | Jan 18 | Mar 1 |
| 28°F | Dec 22 | Jan 9 | Feb 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 |
|---|---|---|---|
| 36°F | Nov 24 | Dec 11 | Jan 4 |
| 32°F | Dec 1 | Dec 28 | Feb 1 |
| 28°F | Dec 14 | Jan 7 | Feb 5 |
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 | 250 days | 292 days | 334 days |
| 32°F | 294 days | 342 days | 365 days |
| 28°F | 345 days | 365 days | 365 days |
| 24°F | 365 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 99% |
| 32°F | 77% |
| 28°F | 26% |
| 24°F | 2% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 85173 | 9b | 25 to 30°F | 5 km |
| 85137 | 9b | 25 to 30°F | 20 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 USC00028348, at 33.3003, -111.0972, elevation 872 m (2,860 ft).
- Data quality: Representative (10+ years), 12 years of freeze data.
- Average days per year at or below 32°F: 3.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Miami (24 km)
- Globe #3 (30 km)
- Roosevelt 1 S (39 km)
- Florence (40 km)
- Apache Junction 5 NE (40 km)
- Mormon Flat (43 km)
- Stewart Mountain Dam (50 km)
- E Mesa (53 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.