Free U.S. Frost Date Dataset
Last and first frost dates for 7,247 U.S. weather stations in one clean CSV file, ready for spreadsheets, maps and articles.
License
Free to use, share and adapt, including commercially, under CC BY 4.0. Please credit Home Garden Lot with a link to this page. The underlying NOAA normals are U.S. public domain.
Suggested citation
Fields
| Column | Meaning |
|---|---|
station_id | NOAA GHCN-Daily station ID |
station_name | Station name (NOAA abbreviations expanded) |
state | Two-letter state code |
latitude, longitude | Station location (decimal degrees) |
elevation_ft | Station elevation in feet |
last_frost_32f_median | Spring date with a 50% chance of a later 32°F freeze (MM-DD) |
last_frost_32f_10pct_risk | Spring date with a 10% chance of a later 32°F freeze |
last_frost_32f_90pct_risk | Spring date with a 90% chance of a later 32°F freeze |
first_frost_32f_median | Fall date with a 50% chance of an earlier 32°F freeze |
first_frost_32f_10pct_risk / 90pct_risk | Fall dates with a 10% / 90% chance of an earlier 32°F freeze |
last_hard_freeze_28f_median, first_hard_freeze_28f_median | Median spring and fall 28°F dates |
frost_free_days_median | Median days between the last spring and first fall 32°F freeze |
years_of_data | Years of 1991–2020 data behind the statistic |
Special values
- rare: 32°F nights were too infrequent in 1991–2020 to compute a date (frost-free in most years).
- all: a freeze is possible in any month (no reliable frost-free season).
- Empty: NOAA did not publish that statistic for the station.
How it was built
We read every station file in NOAA's 1991–2020 annual/seasonal normals archive, kept U.S. stations that publish 32°F freeze probabilities, and converted the dates to a consistent format. The build script is open source and runs automatically, so the file always matches the live tools. Last built 2026-10-29.
Journalists and educators: if you need a state-level summary or a custom cut of the data, get in touch.