Frost Date Calculator · NOAA + NWS
First & Last Frost Dates by Location
Separate the historical freeze odds from the weather that is actually forecast for the next seven days.
NOAA 1991–2020 climatology
—cautious spring date · 10% late-freeze risk
—median last 32°F freeze
—median first 32°F freeze
What the current forecast says
—lowest hourly temperature · next 7 days
—hours at or below 32°F returned by NWS
—hours at or below 28°F
Gardening in Michigan? The deeper Michigan Frost Dates tool uses the established Michigan station network and local gardening pages.
What “10%” actually means
The spring 10% date is not “frost-free.” It means only 10% of historical years in the NOAA normals record had a 32°F freeze on that date or later. The 50% date is the historical median.
For an immediate gardening decision, the live NWS forecast outranks the calendar.
Why station distance matters
Freeze climatology comes from the nearest usable NOAA normals station. A distant station is useful regional context, but terrain, elevation, shoreline influence and cold-air drainage can make your yard different.
Sources: NOAA NCEI Climate Normals and NWS forecasts.