Frost dates for Tohono Chul, AZ
At Tohono Chul, the median last spring frost (32°F) is Feb 26 and the median first fall frost is Dec 4, for a typical growing season of 279 days. For a 90% chance that the last frost has passed, wait until Mar 18. Nearby ZIP codes are in USDA hardiness zones 9a to 9b.
- Feb 26Last spring frost (median)50% chance of 32°F after this date
- Mar 18Safer planting date10% chance of 32°F after this date
- Dec 4First fall frost (median)50% chance of 32°F by this date
- 279 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 28 | Mar 17 | Apr 9 |
| 32°F | Jan 29 | Feb 26 | Mar 18 |
| 28°F | Dec 31 | Feb 1 | Feb 27 |
| 24°F | Dec 16 | Jan 13 | Feb 14 |
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 2 | Nov 21 | Dec 6 |
| 32°F | Nov 17 | Dec 4 | Dec 19 |
| 28°F | Nov 30 | Dec 17 | Jan 16 |
| 24°F | Dec 10 | Jan 2 | 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 | 216 days | 245 days | 271 days |
| 32°F | 252 days | 279 days | 312 days |
| 28°F | 287 days | 320 days | 351 days |
| 24°F | 322 days | 361 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 97% |
| 24°F | 57% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 85704 | 9a | 20 to 25°F | 0 km |
| 85741 | 9a | 20 to 25°F | 6 km |
| 85742 | 9b | 25 to 30°F | 9 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 USC00028590, at 32.3392, -110.9808, elevation 770 m (2,527 ft).
- Data quality: Estimated from nearby stations (2+ years), 5 years of freeze data.
- Average days per year at or below 32°F: 20.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Tucson Camp Ave Exp. (7 km)
- Tucson U Of A #1 (9 km)
- Catalina State Park (10 km)
- Tucson WFO (12 km)
- Tucson 11 W (21 km)
- Tucson 17 NW (22 km)
- Tucson Intl Airport (23 km)
- Mount Lemmon Willow Canyon (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.