Frost dates for Portal 4 SW, AZ
At Portal 4 SW, the median last spring frost (32°F) is May 3 and the median first fall frost is Oct 25, for a typical growing season of 174 days. For a 90% chance that the last frost has passed, wait until May 16. Nearby ZIP codes are in USDA hardiness zone 8a.
- May 3Last spring frost (median)50% chance of 32°F after this date
- May 16Safer planting date10% chance of 32°F after this date
- Oct 25First fall frost (median)50% chance of 32°F by this date
- 174 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 | May 1 | May 15 | May 30 |
| 32°F | Apr 16 | May 3 | May 16 |
| 28°F | Mar 30 | Apr 16 | May 5 |
| 24°F | Mar 3 | Mar 26 | Apr 17 |
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 1 | Oct 14 | Oct 26 |
| 32°F | Oct 11 | Oct 25 | Nov 6 |
| 28°F | Oct 21 | Nov 4 | Nov 18 |
| 24°F | Nov 1 | Nov 15 | Nov 30 |
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 | 130 days | 150 days | 169 days |
| 32°F | 156 days | 174 days | 193 days |
| 28°F | 179 days | 202 days | 225 days |
| 24°F | 209 days | 233 days | 261 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 88056 | 8a | 10 to 15°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 USC00026716, at 31.8833, -109.2056, elevation 1643 m (5,390 ft).
- Data quality: Representative (10+ years), 25 years of freeze data.
- Average days per year at or below 32°F: 136.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Paradise (6 km)
- Chiricahua National Monument (20 km)
- San Simon (46 km)
- Mc Neal (54 km)
- Bowie (56 km)
- Pearce - Sunsites (60 km)
- Douglas Bisbee Inl Airport (61 km)
- Douglas (68 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.