Frost Date Probability: Your Odds of Frost by Week

Updated October 20, 2026

A frost date is an average, so frost can still come after it. NOAA publishes the odds: for each weather station, last spring frost and first fall frost dates at nine probability levels from 10% to 90%, for 32°F and 28°F nights (1991–2020 Climate Normals). Enter your ZIP code to see them for the nearest station.

How to read the odds

• Dates in the table are NOAA’s. In fall, the 10% date is when the first 32°F night has come in 1 of 10 years; NOAA calls it the “10% probability date of first 32F occurrence or earlier” (NOAA NCEI, Annual/Seasonal Normals documentation). In spring it works the other way: after the 10% date, a 32°F night still comes in only 1 of 10 years, and after the 90% date in 9 of 10.
• Week-by-week numbers between NOAA’s levels are our estimate. NOAA publishes nine levels (10%, 20% ... 90%). For weeks that fall between two levels, we draw a straight line between them, and those weeks are labeled “our estimate.”
• Where frost is rare, we show how often a 32°F night happens (“frost in X% of years”) instead of dates, because there is no typical frost date.
• 32°F and 28°F: 32°F is a light frost that hurts tender plants; 28°F is a hard freeze. 28°F odds appear where a 28°F night happens in at least some years and NOAA lists the dates.

For planting dates built from the 50% (median) frost dates, use the ZIP planting calendar; for typical dates by town, see frost dates.

Data: NOAA NCEI, U.S. Climate Normals (1991–2020), per-station freeze probability normals (ANN-TMIN-PRBLST and PRBFST, 32°F and 28°F, 10–90%, and PRBOCC). Each ZIP code (Census 2023 ZCTA centroid) uses the nearest station with freeze records within 60 miles.