Frost dates for Mount Lemmon Willow Canyon, AZ
At Mount Lemmon Willow Canyon, the median last spring frost (32°F) is Apr 1 and the median first fall frost is Nov 19, for a typical growing season of 229 days. For a 90% chance that the last frost has passed, wait until Apr 21. Nearby ZIP codes are in USDA hardiness zone 8b.
- Apr 1Last spring frost (median)50% chance of 32°F after this date
- Apr 21Safer planting date10% chance of 32°F after this date
- Nov 19First fall frost (median)50% chance of 32°F by this date
- 229 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 | Apr 3 | Apr 17 | May 4 |
| 32°F | Mar 13 | Apr 1 | Apr 21 |
| 28°F | Feb 19 | Mar 12 | Apr 6 |
| 24°F | Jan 3 | Feb 20 | Mar 11 |
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 | Oct 19 | Nov 5 | Nov 24 |
| 32°F | Oct 30 | Nov 19 | Dec 4 |
| 28°F | Nov 11 | Nov 30 | Dec 17 |
| 24°F | Nov 24 | Dec 14 | Jan 26 |
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 | 177 days | 199 days | 223 days |
| 32°F | 203 days | 229 days | 254 days |
| 28°F | 230 days | 261 days | 289 days |
| 24°F | 264 days | 296 days | 343 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 98% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 85619 | 8b | 15 to 20°F | 4 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 USC00025737, at 32.3858, -110.6981, elevation 2142 m (7,027 ft).
- Data quality: Estimated from nearby stations (2+ years), 3 years of freeze data.
- Average days per year at or below 32°F: 53.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Catalina State Park (22 km)
- Saguaro National Park (23 km)
- Oracle 2 SE (24 km)
- San Manuel (25 km)
- Oracle State Park (25 km)
- Tucson Camp Ave Exp. (26 km)
- Tohono Chul (27 km)
- Tucson WFO (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.