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 03303
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 03303 in zone 5b (the coldest night of a typical year: -15 to -10°F).
The nearest station, Salisbury, NH, is 5 miles from the ZIP's center: its last spring frost comes after May 14 in half of years and after May 28 in one year in ten. By the USDA's method its plant hardiness zone is 6a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Salisbury, NH | 5 mi | 550 ft | May 14 | May 28 | September 29 | 6a |
| Hopkinton Lake, NH | 9 mi | 430 ft | May 6 | May 20 | October 1 | – |
| Franklin, NHFranklin Falls Dam | 11 mi | 450 ft | May 7 | May 20 | October 3 | – |
| Concord, NHConcord Municipal Airport | 12 mi | 346 ft | May 8 | May 22 | October 3 | 5b |
| Weare (2 mi NE), NH | 15 mi | 805 ft | May 9 | May 23 | October 5 | – |
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 Salisbury
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 6 | June 1 | May 27 | May 12 | September 20 | September 6 |
| 32°F | May 28 | May 20 | May 14 | April 30 | September 29 | September 14 |
| 28°F (hard freeze) | May 16 | May 6 | April 30 | April 18 | October 9 | September 26 |
| 24°F | April 30 | April 21 | April 16 | April 3 | October 27 | October 6 |
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.