Frost dates for Portland Intl Airport, OR
At Portland Intl Airport, the median last spring frost (32°F) is Mar 13 and the median first fall frost is Nov 19, for a typical growing season of 247 days. For a 90% chance that the last frost has passed, wait until Apr 1. Nearby ZIP codes are in USDA hardiness zones 8b to 9a.
- Mar 13Last spring frost (median)50% chance of 32°F after this date
- Apr 1Safer planting date10% chance of 32°F after this date
- Nov 19First fall frost (median)50% chance of 32°F by this date
- 247 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 | Mar 22 | Apr 6 | Apr 25 |
| 32°F | Feb 22 | Mar 13 | Apr 1 |
| 28°F | Jan 4 | Feb 16 | Mar 6 |
| 24°F | Dec 7 | Jan 13 | Feb 19 |
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 18 | Nov 2 | Nov 22 |
| 32°F | Oct 29 | Nov 19 | Dec 10 |
| 28°F | Nov 12 | Dec 5 | Jan 10 |
| 24°F | Nov 24 | Dec 21 | Feb 1 |
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 | 184 days | 210 days | 234 days |
| 32°F | 219 days | 247 days | 277 days |
| 28°F | 263 days | 298 days | 337 days |
| 24°F | 306 days | 342 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 98% |
| 24°F | 69% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 97218 | 9a | 20 to 25°F | 2 km |
| 97211 | 9a | 20 to 25°F | 3 km |
| 98664 | 8b | 15 to 20°F | 4 km |
| 98684 | 8b | 15 to 20°F | 8 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 USW00024229, at 45.5908, -122.6003, elevation 6 m (19 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 32.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Portland WFO (6 km)
- Portland Kgw-Tv (11 km)
- Portland Troutdale Airport (16 km)
- Troutdale (17 km)
- Nature Park-Beaverton (21 km)
- Beaverton 2 SSW (23 km)
- Oregon City (26 km)
- Portland-Hillsboro Airport (28 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.