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 97123
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 97123 in zone 8b (the coldest night of a typical year: 15 to 20°F).
The nearest station, Hillsboro, OR, is 7 miles from the ZIP's center: its last spring frost comes after April 16 in half of years and after May 3 in one year in ten. By the USDA's method its plant hardiness zone is 8b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Hillsboro, ORPortland-Hillsboro Airport | 7 mi | 204 ft | April 16 | May 3 | October 23 | 8b |
| Beaverton, OR2 mi SSW | 8 mi | 270 ft | April 1 | April 26 | November 6 | – |
| Nature Park-Beaverton, OR | 8 mi | 185 ft | February 11 | March 5 | December 5 | – |
| Forest Grove, OR | 8 mi | 180 ft | April 16 | May 5 | October 26 | 8a |
| Rex (1 mi S), OR | 10 mi | 515 ft | March 21 | April 19 | November 22 | – |
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 Hillsboro
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 27 | May 14 | May 5 | April 21 | October 6 | September 20 |
| 32°F | May 3 | April 25 | April 16 | March 25 | October 23 | October 3 |
| 28°F (hard freeze) | April 9 | March 24 | March 13 | February 15 | November 12 | October 20 |
| 24°F | March 5 | February 23 | February 14 | December 31 | December 1 | November 4 |
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.