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 97030
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 97030 in zone 9a (the coldest night of a typical year: 20 to 25°F).
The nearest station, Portland Troutdale Airport, OR, is 3 miles from the ZIP's center: its last spring frost comes after March 16 in half of years and after April 12 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 Troutdale Airport, OR | 3 mi | 29 ft | March 16 | April 12 | November 20 | 9a |
| Troutdale, OR | 4 mi | 33 ft | March 26 | April 21 | November 17 | 9a |
| Portland Weather Office, OR | 6 mi | 21 ft | March 13 | April 5 | November 22 | – |
| Portland, ORPortland International Airport | 10 mi | 19 ft | March 13 | April 1 | November 19 | 9a |
| Portland Kgw-Tv, OR | 12 mi | 159 ft | February 25 | March 21 | December 1 | 9a |
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 Troutdale Airport
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) | May 4 | April 28 | April 19 | March 27 | October 30 | October 11 |
| 32°F | April 12 | March 27 | March 16 | February 18 | November 20 | October 30 |
| 28°F (hard freeze) | March 10 | February 25 | February 14 | December 27 | December 15 | November 15 |
| 24°F | February 20 | February 4 | January 22 | December 6 | January 1 | 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.