Frost dates for Robson Rch, AZ
At Robson Rch, the median last spring frost (32°F) is Feb 7 and the median first fall frost is Dec 3, for a typical growing season of 298 days. For a 90% chance that the last frost has passed, wait until Mar 4. Nearby ZIP codes are in USDA hardiness zone 9a.
- Feb 7Last spring frost (median)50% chance of 32°F after this date
- Mar 4Safer planting date10% chance of 32°F after this date
- Dec 3First fall frost (median)50% chance of 32°F by this date
- 298 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 3 | Mar 3 | Mar 22 |
| 32°F | Jan 10 | Feb 7 | Mar 4 |
| 28°F | Dec 19 | Jan 17 | Feb 17 |
| 24°F | Dec 13 | Jan 7 | Feb 5 |
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 6 | Nov 21 | Dec 7 |
| 32°F | Nov 17 | Dec 3 | Dec 21 |
| 28°F | Nov 27 | Dec 17 | Jan 15 |
| 24°F | Dec 8 | Dec 30 | Jan 27 |
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 | 237 days | 263 days | 290 days |
| 32°F | 268 days | 298 days | 328 days |
| 28°F | 302 days | 334 days | 364 days |
| 24°F | 334 days | 365 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 91% |
| 24°F | 41% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 85194 | 9a | 20 to 25°F | 10 km |
| 85123 | 9a | 20 to 25°F | 12 km |
| 85122 | 9a | 20 to 25°F | 16 km |
| 85131 | 9a | 20 to 25°F | 18 km |
| 85193 | 9a | 20 to 25°F | 20 km |
| 85128 | 9a | 20 to 25°F | 20 km |
| 85191 | 9a | 20 to 25°F | 26 km |
| 85141 | 9a | 20 to 25°F | 26 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 USC00027187, at 32.8117, -111.6314, elevation 456 m (1,495 ft).
- Data quality: Representative (10+ years), 10 years of freeze data.
- Average days per year at or below 32°F: 18.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Arizona City (11 km)
- Eloy 4 NE (11 km)
- Casa Grande (11 km)
- Casa Grande National Monument (22 km)
- Picacho 8 SE (28 km)
- Florence (34 km)
- Chandler Heights (44 km)
- Maricopa 4 N (50 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.