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 98166
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 98166 in zone 9a (the coldest night of a typical year: 20 to 25°F).
The nearest station, Seattle, WA, is 2 miles from the ZIP's center: its last spring frost comes after March 2 in half of years and after March 23 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 |
|---|---|---|---|---|---|---|
| Seattle, WASeattle Tacoma International Airport | 2 mi | 370 ft | March 2 | March 23 | November 23 | 9a |
| Kent, WA | 6 mi | 30 ft | March 20 | April 8 | November 10 | 8b |
| Seattle Boeing Field, WA | 6 mi | 20 ft | March 13 | April 1 | November 17 | 9a |
| Renton, WARenton Municipal Airport | 7 mi | 29 ft | March 13 | March 31 | November 16 | 9a |
| Tacoma #1, WA | 14 mi | 25 ft | March 8 | March 31 | November 14 | 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 Seattle
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 6 | March 31 | March 13 | November 7 | October 24 |
| 32°F | March 23 | March 12 | March 2 | February 5 | November 23 | November 6 |
| 28°F (hard freeze) | February 28 | February 18 | February 4 | December 20 | December 10 | November 17 |
| 24°F | February 17 | January 25 | January 4 | December 5 | December 17 | November 26 |
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.