Frost date tool
First and last frost date calculator by ZIP Code
Enter a US ZIP Code to estimate your usual last spring freeze and first fall freeze. The results use long-term NOAA weather records near your area.
We use your ZIP Code to find nearby long-term weather records. The application does not save your ZIP Code in a user database.
Why you will see three date choices
Weather changes from year to year, so no frost date is guaranteed. The middle estimate fits a typical risk level. The more cautious dates leave a larger safety margin for an unusually late spring freeze or early fall freeze.
Why your garden may differ
A nearby weather station cannot capture every hill, low spot, city heat island or sheltered yard. Treat the dates as a starting point, then check the current forecast and conditions in your own garden.
Where the estimates come from
The calculator uses NOAA's 1991-2020 records for days when the air temperature reached 32°F or lower. It finds a nearby station with enough complete years to support all three planning levels.
View technical matching details
- The source is NOAA 1991-2020 U.S. Climate Normals v1.0.1, using the 32°F agricultural probability fields.
- A station must provide all six spring and fall dates, NOAA S completeness and at least 24 years of observations.
- A ZIP Code is approximated by its 2025 Census ZCTA center, then matched to the closest station by straight-line distance over the earth.
- The tool returns no result when the closest eligible station is more than 100 miles away.
Sources: 1991-2020 U.S. Climate Normals and 2025 Gazetteer ZCTA National File. Data pipeline reviewed 2026-07-17.