Frost dates by ZIP code: The nearest NOAA stations to your ZIP, 1991-2020 normals
Enter a five-digit ZIP code. PlainClimate finds its center (Census Bureau 2024) and the five nearest NOAA stations with frost dates, and shows each station's last spring and first autumn 32°F dates with its distance and elevation.
Frost dates near ZIP 97221
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 97221 in zone 8b (the coldest night of a typical year: 15 to 20°F).
The nearest station, Portland Kgw-Tv, OR, is 2 miles from the ZIP's center: its last spring frost comes after February 25 in half of years and after March 21 in one year in ten. By the USDA's method its plant hardiness zone is 9a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Portland Kgw-Tv, OR | 2 mi | 159 ft | February 25 | March 21 | December 1 | 9a |
| Beaverton, OR2 mi SSW | 5 mi | 270 ft | April 1 | April 26 | November 6 | – |
| Nature Park-Beaverton, OR | 5 mi | 185 ft | February 11 | March 5 | December 5 | – |
| Portland, ORPortland International Airport | 9 mi | 19 ft | March 13 | April 1 | November 19 | 9a |
| Vancouver, WAVancouver Pearson Airport | 9 mi | 30 ft | March 29 | April 18 | November 9 | 8b |
Frost comes later in spring at higher and colder stations and earlier in low, open ground: prefer a station at a similar elevation to yours. Hardiness zone in the table: the USDA's rule (the average of each year's coldest night, 1991-2020) applied to the station's own record.
Every frost threshold at Portland Kgw-Tv
NOAA publishes the dates for several temperatures and odds. A 30% spring date means a 3-in-10 chance of a later frost (the convention almanacs use); 50% is the median; 10% the cautious date.
| Threshold | Spring, 10% | Spring, 30% | Spring, 50% | Spring, 90% | Autumn, 50% | Autumn, 10% |
|---|---|---|---|---|---|---|
| 36°F (light frost) | April 21 | April 5 | March 29 | March 7 | November 12 | October 28 |
| 32°F | March 21 | March 6 | February 25 | January 24 | December 1 | November 10 |
| 28°F (hard freeze) | February 26 | February 10 | January 31 | December 21 | December 20 | November 25 |
| 24°F | February 18 | February 1 | January 15 | December 8 | December 29 | November 30 |
Source: NOAA NCEI 1991-2020 annual normals; ZIP centers: Census Bureau 2024 Gazetteer; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. Autumn 10%: one year in ten has its first frost before this date.