Last Frost Date By Zip Code
without the guesswork.
Frost Date Calculator By Zip — Match a ZIP to nearby NOAA 1991–2020 32°F probability dates, with the station, distance and USDA zone kept explicit. Uses a focused calculator with visible assumptions. Inputs stay in your browser.
CalcSpan matches the ZIP locally to a nearby NOAA 1991–2020 climate-normal station, then applies the selected probability threshold. USDA hardiness zone is shown separately and never used to invent frost dates.
Calculate to load the current reference data before saving.
Context matters.
- A ZIP is a search aid, not a weather station. If the automatic station differs materially in elevation, coast exposure or terrain, use the NOAA station override.
- USDA hardiness zones summarize annual extreme minimum temperature and are not frost dates.
Sources & scope
This page shows the source trail, jurisdiction and review date alongside the result. Always confirm time-sensitive rules with the linked authority.
What to know before using the result.
Is a USDA hardiness zone the same as a frost date?
No. USDA zones describe annual extreme minimum temperature for perennial-plant cold tolerance. CalcSpan obtains 32°F probability dates from NOAA climate normals and shows the zone only as a separate reference.
What does the 10% freeze-risk threshold mean?
At the selected NOAA station, there is a 10% modeled chance the last spring 32°F event occurs later than the shown spring date, and a 10% chance the first fall event occurs earlier than the shown fall date.
Why does the calculator show a NOAA station and distance?
Frost normals are calculated at weather stations, not ZIP codes. Distance, elevation, coast exposure, slope and cold-air drainage help you judge whether the automatically matched station represents your site.