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 99688
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 99688 in zone 3b (the coldest night of a typical year: -35 to -30°F).
The nearest station, Willow, AK, is 17 miles from the ZIP's center: its last spring frost comes after May 15 in half of years and after May 28 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Willow, AKWillow West | 17 mi | 205 ft | May 15 | May 28 | September 18 | – |
| Whites Crossing, AK | 18 mi | 270 ft | May 29 | June 9 | September 7 | – |
| Little Su At Hatcher Pass Bridge, AK | 18 mi | 902 ft | May 18 | May 30 | September 18 | – |
| North Lakes, AKAnderson Lake | 20 mi | 458 ft | May 16 | May 31 | September 23 | – |
| Matanuska Experiment Farm, AK | 25 mi | 172 ft | May 14 | May 26 | September 20 | 4b |
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 Willow
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) | June 9 | June 1 | May 28 | May 15 | September 7 | August 25 |
| 32°F | May 28 | May 21 | May 15 | May 3 | September 18 | September 4 |
| 28°F (hard freeze) | May 17 | May 8 | May 3 | April 21 | September 27 | September 14 |
| 24°F | May 6 | April 30 | April 24 | April 12 | October 5 | September 23 |
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.