Your average last frost date is the spring day after which, in half of years, the temperature no longer drops to 32 °F; the first frost date is the same in fall. They are averages, so 1 year in 2 brings a frost later in spring (or earlier in fall). For tender plants, the 1-in-10 date the finder also shows is the safer bet.
How to read the odds
NOAA’s normals give each station’s freeze dates at several probabilities. The finder shows three of them:
- Last spring frost, 50%: half of years have a 32 °F night after this date. Extension Dane County, Wisconsin, reminds gardeners that this median still leaves a 50% chance of frost after it, and sets seedlings out a few days later.
- 1 year in 10: the date after which a spring frost comes only 1 year in 10, and in fall, the date before which an early frost comes only 1 year in 10.
- Growing season: the number of frost-free days between the last and first frost in at least half of years.
The timeline under your result shades the whole year: blue where frost is likely, green where it is very unlikely, and the change in odds between them.
Frost, freeze and hard freeze
- Freeze, 32 °F: the threshold NOAA’s frost dates use. The National Weather Service calls it a freeze when the air reaches 32 °F or below over a wide area.
- Hard freeze, 28 °F: the NWS defines it as 28 °F or lower for an extended time, which kills most types of vegetation. The finder shows these dates too.
- Frost on warmer nights: frost can form on clear, calm nights even when the official low is above freezing; the NWS office in Raleigh issues frost advisories for lows of 33 to 36 °F.
How to use your frost dates
- Start seeds indoors by counting back. Extension Dane County starts tomatoes and peppers 6 to 8 weeks before the last frost date. The University of Maryland gives tomatoes 5 to 6 weeks and peppers 8 to 10 before they go outside.
- Set tender plants out after the last frost. The University of Minnesota transplants tomatoes once all danger of frost has passed and the soil has warmed. Waiting for the 1-in-10 date cuts the risk to 1 year in 10.
- Plan the fall: count back from the first frost to see whether a late crop has time to ripen. In cold zones, garlic goes in one to three weeks after the first frost (University of Minnesota, SDSU).
Why your garden may frost on a different night
The dates come from one weather station near you, named under your result. Your yard can be colder or warmer:
- Low spots are colder. Cold air is heavier than warm air and flows down into low areas, where frost damage is worse (Penn State Extension).
- Clear, calm nights are the risk. Radiation frosts form when the ground loses its heat on still nights, and are less likely when it’s cloudy (Penn State Extension).
- Hills change everything. A station a few hundred feet higher or lower than you can differ by days or weeks. The finder picks the nearby station lowest in elevation unless another is much closer, since most homes sit in a ZIP code’s valleys and towns.
Frost dates for major cities
Average dates (50%) for the downtown ZIP code of 30 cities, from the station the finder uses there:
| City | Zone | Last spring frost | First fall frost | Growing season | NOAA station |
|---|---|---|---|---|---|
| Albuquerque, NM | 7b | Apr 18 | Oct 24 | 189 days | Albuquerque Valley, NM |
| Anchorage, AK | 5a | May 1 | Sep 29 | 150 days | Anchorage Merrill Fld, AK |
| Atlanta, GA | 8a | Mar 15 | Nov 20 | 252 days | Atlanta Hartsfield Intl AP, GA |
| Austin, TX | 9a | Feb 20 | Dec 3 | 291 days | Austin-Camp Mabry, TX |
| Boise, ID | 7a | Apr 24 | Oct 21 | 179 days | Boise Air Terminal, ID |
| Boston, MA | 7a | Apr 4 | Nov 9 | 218 days | Boston Logan Intl AP, MA |
| Charlotte, NC | 8a | Mar 30 | Nov 3 | 221 days | Charlotte Douglas AP, NC |
| Chicago, IL | 6b | Apr 10 | Nov 5 | 208 days | Chicago Northerly Is, IL |
| Columbus, OH | 6b | Apr 20 | Oct 24 | 185 days | Columbus Wcmh, OH |
| Dallas, TX | 8b | Mar 2 | Nov 29 | 272 days | Dallas Love Fld, TX |
| Denver, CO | 6a | Apr 30 | Oct 12 | 165 days | Denver Water Dept, CO |
| Detroit, MI | 6b | Apr 21 | Oct 31 | 190 days | Detroit City AP, MI |
| Houston, TX | 9b | Feb 2 | Dec 25 | 327 days | Houston-Port, TX |
| Indianapolis, IN | 6b | Apr 15 | Oct 26 | 193 days | Indianapolis, IN |
| Kansas City, MO | 6b | Apr 4 | Nov 2 | 211 days | Kansas City Downtown AP, MO |
| Las Vegas, NV | 9b | Feb 1 | Dec 8 | 311 days | N Las Vegas, NV |
| Los Angeles, CA | 10b | None | None | all year | Los Angeles Dwtn Usc Campus, CA |
| Minneapolis, MN | 5a | Apr 23 | Oct 16 | 175 days | Lower St Anthony Falls, MN |
| Nashville, TN | 7b | Apr 1 | Oct 31 | 213 days | Shelby Bottoms Nature, TN |
| New York, NY | 7b | Mar 30 | Nov 20 | 236 days | New York Cntrl Pk Twr, NY |
| Oklahoma City, OK | 7b | Apr 4 | Nov 2 | 213 days | Oklahoma City Will Rogers AP, OK |
| Philadelphia, PA | 7b | Mar 30 | Nov 17 | 232 days | Phila Franklin Inst, PA |
| Phoenix, AZ | 10a | Rare | Rare | about all year | Phoenix Sky Harbor Intl AP, AZ |
| Portland, OR | 9a | Feb 25 | Dec 1 | 280 days | Portland Kgw-Tv, OR |
| Raleigh, NC | 8a | Mar 28 | Nov 8 | 229 days | Raleigh State Univ, NC |
| Sacramento, CA | 9b | Jan 12 | Dec 16 | 341 days | Sacramento 5 Ese, CA |
| Salt Lake City, UT | 7b | Apr 8 | Oct 31 | 204 days | Salt Lake City Intl AP, UT |
| Seattle, WA | 9a | Mar 8 | Nov 23 | 259 days | Seattle Sand Pt Wsfo, WA |
| St. Louis, MO | 7a | Apr 6 | Oct 27 | 203 days | Cahokia, IL |
| Washington, DC | 8a | Mar 29 | Nov 8 | 224 days | Natl Arboretum Dc, MD |
“Rare” means a freeze comes only in some winters, in a short midwinter window; “None” means no freeze in most years. Enter a ZIP code above for the odds and the hard-freeze dates.
Questions people ask
When is the last frost in my area?
Enter your ZIP code above. The finder gives the average date and the date after which frost comes only 1 year in 10.
Is it safe to plant after the last frost date?
Not quite: half of years still bring a frost after the average date. Wait a few days to a week or two, or plant by the 1-in-10 date, and keep a cover handy for a cold night.
When is the first frost in fall?
The finder shows the average first fall frost and the date before which an early frost comes only 1 year in 10.
Why do other sites show different frost dates?
They may use older normals (1981–2010), a different station or a different temperature, such as 28 °F or 36 °F. Ours are NOAA’s 1991–2020 normals at 32 °F, and we name the station.
Do frost dates change from year to year?
Every year’s actual frost is different; these are 30-year averages. NOAA updates its normals every ten years, and 1991–2020 is the newest set.
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020: annual freeze-date probabilities by station (first fall and last spring dates at 32 °F and 28 °F, growing-season length), from the annual/seasonal normals and their documentation.
- ZIP code centers: U.S. Census Bureau, 2024 Gazetteer files (ZIP code tabulation areas). Zones: PRISM Group, Oregon State University, prism.oregonstate.edu, accessed October 11, 2026.
- National Weather Service, Glossary: freeze, hard freeze; NWS Raleigh, Frost and freeze information: frost advisories for lows of 33–36 °F.
- Extension Dane County, University of Wisconsin–Madison, It’s Time to Start Seeds (Lisa A. Johnson): the last frost date is a median with a 50% chance of frost after it; tomatoes and peppers 6–8 weeks before it.
- University of Maryland Extension, Starting Vegetable Seeds Indoors: tomatoes 5–6 weeks, peppers and eggplant 8–10 weeks before transplanting.
- University of Minnesota Extension, Growing tomatoes in home gardens: transplant after all danger of frost has passed and the soil has warmed. Garlic timing: see when to plant garlic.
- Penn State Extension, Frost, Critical Temperatures, and Frost Protection (Rob Crassweller, 2024): radiation frost on clear, calm nights; cold air flows into low areas.