Frost dates by ZIP code

How to read your frost dates

Frost dates are probabilities, not promises. NOAA looks at every year in its 1991–2020 record for a station and works out how often the last spring freeze (or the first fall freeze) falls before or after each date. The tool shows three of those dates for each freeze:

• Typical (median). Half of years have a later last spring frost and half an earlier one. This is what most charts call the “average last frost date”.
• Late year (1 year in 10). In spring, a freeze after this date happens in about 1 year out of 10, so it is the cautious date for tender transplants. In fall, it is the date by which frost has arrived in 9 years out of 10.
• Early year (1 year in 10). In spring, the last frost comes this early in only about 1 year in 10. In fall, there is a 1-in-10 chance of frost by this date, so plan fall crops to be ready before it.

32°F frost vs. 28°F hard freeze

The 32°F row is the usual “frost date”: the first or last night the station’s low reached 32°F or colder. Tender crops like tomatoes, peppers, basil, beans and squash can be damaged at that point. The 28°F row marks harder freezes. Many cool-season crops shrug off a light frost but can be hurt as lows drop toward the upper 20s, so the 28°F dates help you judge how long kale, cabbage, carrots and other hardy crops can stay out in fall. Where a cell says “too rare”, NOAA had too few freezes at that threshold to compute a date.

Growing season length

The frost-free season is the number of days between the last spring and first fall 32°F freeze. The tool shows the median length and the length you can count on in 9 years out of 10. Compare it with the “days to maturity” on seed packets, and remember that slow crops such as winter squash, sweet potatoes and peppers need most of that season, so starting some of them indoors helps.

Frost dates for major US cities

Median 32°F dates from the NOAA station nearest each city’s downtown ZIP code. Click a city to see its full table, including the 1-in-10-year dates.

Where the data comes from

Frost dates come from the NOAA National Centers for Environmental Information (NCEI) U.S. Climate Normals for 1991–2020, using the annual freeze-probability normals (last spring and first fall dates at 32°F and 28°F at 10%, 50% and 90% probability, the 32°F growing-season length and the chance of any freeze in a year). ZIP code locations are the internal points of ZIP Code Tabulation Areas from the US Census Bureau 2026 Gazetteer Files. We match each ZIP code to the nearest of 7,277 NOAA stations in the 50 states, Puerto Rico and the US Virgin Islands that have freeze data, by straight-line distance. One exception: a few stations sit on mountain summits or in cold high valleys where a freeze can happen in any month; if one of those is nearest and a station with normal frost dates is not much farther away, we use that station instead. All lookups run in your browser from files on this site; we do not send your ZIP code anywhere.

NOAA marks some stations as having freezes too rare to compute dates (much of South Florida, Hawaii, Puerto Rico and coastal Southern California) and some as having freeze risk in every month (high mountain sites). The tool says so instead of showing a date.

Microclimates and why your garden may differ

These are long-term station averages, not a forecast. Your garden can run colder or warmer than the station: low spots and valleys collect cold air, hilltops and spots near large lakes or the coast often stay milder, and cities hold heat. Elevation matters too, so check the station elevation shown with your result against your own. The 1991–2020 period also smooths over recent years. For the most local advice, ask your county cooperative extension office, and always check the 7-day forecast before setting out tender plants; a frost blanket or row cover buys a few degrees on a cold night.

Next steps: the week-by-week planting calendar by frost date, when to plant tomatoes and what to plant in fall.

Frequently asked questions

What is the average last frost date?

It is the median date of the last 32°F night in spring at the weather station nearest you: in half of years the last frost comes earlier and in half it comes later. Because of that, there is still roughly a 50% chance of frost after the average date.

Should I plant on my average last frost date?

Cool-season crops can go in before it, but tender crops such as tomatoes, peppers and basil are safer after it. For a cautious plan, use the late-year (1 in 10) date the tool shows, warm soil, and a check of the local forecast.

Why are my frost dates different from another website?

Sites can use different stations, a different period of years (these use NOAA’s 1991–2020 normals), or a different temperature such as 36°F or 28°F. Distance and elevation between you and the station also matter.

Where do these frost dates come from?

From NOAA NCEI U.S. Climate Normals for 1991–2020 (annual freeze-probability normals) for the station nearest the center of your ZIP code, located with the US Census Bureau Gazetteer ZIP Code Tabulation Areas.

What if the tool says frost is rare where I live?

NOAA could not compute frost dates because 32°F nights are too uncommon at that station. You can plant most of the year; heat and rainfall matter more, so follow a local extension planting calendar.