Frost dates for Tucson U Of A #1, AZ
At Tucson U Of A #1, the median last spring frost (32°F) is Feb 11 and the median first fall frost is Dec 2, for a typical growing season of 293 days. For a 90% chance that the last frost has passed, wait until Mar 7. Nearby ZIP codes are in USDA hardiness zone 9b.
- Feb 11Last spring frost (median)50% chance of 32°F after this date
- Mar 7Safer planting date10% chance of 32°F after this date
- Dec 2First fall frost (median)50% chance of 32°F by this date
- 293 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 | Feb 12 | Mar 6 | Mar 30 |
| 32°F | Jan 16 | Feb 11 | Mar 7 |
| 28°F | Dec 21 | Jan 18 | Feb 17 |
| 24°F | Dec 7 | Dec 31 | Feb 4 |
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 4 | Nov 22 | Dec 6 |
| 32°F | Nov 16 | Dec 2 | Dec 20 |
| 28°F | Nov 29 | Dec 15 | Jan 17 |
| 24°F | Dec 6 | Dec 25 | Jan 29 |
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 | 228 days | 257 days | 285 days |
| 32°F | 263 days | 293 days | 326 days |
| 28°F | 299 days | 336 days | 365 days |
| 24°F | 337 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 90% |
| 24°F | 38% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 85705 | 9b | 25 to 30°F | 2 km |
| 85745 | 9b | 25 to 30°F | 5 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 USC00028817, at 32.2581, -111.0053, elevation 706 m (2,315 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 21.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Tucson WFO (6 km)
- Tucson Camp Ave Exp. (6 km)
- Tohono Chul (9 km)
- Tucson Intl Airport (15 km)
- Tucson 11 W (16 km)
- Tucson 17 NW (18 km)
- Catalina State Park (19 km)
- Saguaro National Park (27 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.