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 98506
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 98506 in zone 8b (the coldest night of a typical year: 15 to 20°F).
The nearest station, Olympia, WA, is 9 miles from the ZIP's center: its last spring frost comes after April 29 in half of years and after May 15 in one year in ten. By the USDA's method its plant hardiness zone is 8a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Olympia, WAOlympia Airport | 9 mi | 188 ft | April 29 | May 15 | October 14 | 8a |
| Shelton, WAShelton Sanderson Field | 16 mi | 271 ft | April 27 | May 12 | October 16 | 8a |
| Tacoma, WATacoma Narrows Airport | 18 mi | 292 ft | March 11 | April 2 | November 21 | 9a |
| Cushman Powerhouse #2, WA | 23 mi | 21 ft | March 24 | April 17 | November 15 | 9a |
| Tacoma #1, WA | 24 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 Olympia
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 31 | May 22 | May 15 | April 30 | September 28 | September 12 |
| 32°F | May 15 | May 5 | April 29 | April 11 | October 14 | September 28 |
| 28°F (hard freeze) | April 29 | April 15 | April 5 | March 12 | November 1 | October 9 |
| 24°F | April 1 | March 18 | March 6 | February 7 | November 20 | October 28 |
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.