First and Last Frost Dates for 129 US Cities (NOAA Data)

Average last spring frost dates in the US range from January in the warmest parts of California, Texas and Louisiana to late May or early June in the mountain West, and first fall frosts run from mid-September to late December. We pulled NOAA's official 1991–2020 freeze statistics for 129 cities in all 50 states: the median city gets about 200 frost-free days a year.

Find your city in the table below, then plant tender crops after its 90% safe date, not the average.

How do you read a frost date?

NOAA gives each freeze date with a probability, based on 30 years of daily low temperatures (1991–2020). We show two for each season:

• Last spring frost (50%): the median date. In half of years, the last 32°F freeze comes later than this. It's the number most planting calendars call the "average last frost."
• 90% safe after: only a 10% chance of a freeze after this date. Use it for tender transplants like tomatoes, peppers, basil and squash.
• First fall frost (50%): in half of years, the first freeze comes earlier than this.
• 90% frost-free until: only a 10% chance of a freeze before this date. Plan fall harvests of tender crops to finish by then.

Across the 121 cities with a regular frost season, the 90% spring date falls 17 days after the median on average (from 10 days in Anchorage to 33 days in San Jose). In fall, the safe date comes about 15 days before the median.

Frost dates for 129 US cities

Want the raw numbers? Download the CSV, which includes each city's NOAA station ID and name.

Which cities have the shortest growing season?

Measured from the median last spring frost to the median first fall frost, the shortest frost-free seasons in our list are in the mountain West, the northern Plains and Alaska. Flagstaff's season is 115 days, less than four months.

In these places, check days to maturity before you buy seeds. A 75-day tomato set out in early June has little room to spare, so many gardeners start seeds indoors and choose short-season varieties.

Which cities have the longest growing season?

Among cities that freeze in most winters, California's Central Valley, the Gulf Coast and the desert Southwest have the longest frost-free seasons: up to 347 days in San Jose.

Phoenix, Tampa and Orlando get freezes so briefly, and not every winter, that their median dates land around the new year. Five cities in our list (Los Angeles, San Diego, San Francisco, Miami and Honolulu) don't see a 32°F freeze in most years at all. In those places, frost isn't what limits the planting calendar; heat, rainfall or cool summers usually are.

Is your garden colder than the airport?

Probably, at least on some nights. Most of these stations are at airports or in city centers, which tend to stay warmer than open countryside. Your own yard can differ from the official date by a week or more:

• Low spots and valleys collect cold air on clear, calm nights.
• Higher elevation is colder. Flagstaff, at about 7,000 ft, has a shorter season than Fairbanks, Alaska.
• Frost can form on plants when the official temperature, measured about 5 ft up, is a few degrees above freezing.
• South-facing walls, paving and nearby water keep some spots warmer.

If a cold night is forecast after you've planted, cover tender plants. Our guide to protecting plants from frost covers row covers, cloches and low tunnels, and a cold frame adds weeks on both ends of the season.

How we built this table

• Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020, annual/seasonal normals by station.
• Threshold: 32°F (a light freeze). NOAA also publishes 28°F "hard freeze" dates, which come later in fall and earlier in spring; they're not included here.
• Stations: for each city we used its main National Weather Service station, usually the primary airport (for New York, Central Park; for Washington, D.C., Reagan National). Station IDs are in the CSV.
• Frost-free days is NOAA's median growing-season length for the 32°F threshold.
• Data retrieved October 5, 2026. Climate normals are updated every 10 years; the 1991–2020 set is the current one.

Use this data

You're free to use the table, chart and CSV in your own articles, apps or planting guides. NOAA's data is public domain; we compiled and checked it. If it helps your readers, please credit Plot & Plank with a link to this page.