GROWING TOOLS
Frost Date Calculator: First & Last Frost by ZIP
Last frost and first frost set the outdoor planting window. A ZIP’s USDA zone says how cold winter gets, not the day you can set tomatoes outside. Enter a ZIP for the median last and first 32°F freeze, the freeze-free days, and how many weeks to start warm-season crops indoors.
A planting window is the stretch between the median last 32°F freeze in spring and the median first 32°F freeze in fall. The figures are NOAA 1991–2020 climate normals for the nearest of 100 large-city stations, not a forecast for this year and not your USDA zone. ZIP 10001 matches the New York station: median last freeze March 30, median first freeze November 20, and 236 freeze-free days. The Minneapolis example is later and shorter: last freeze April 23, first freeze October 18, and 176 days. Denver’s station has a median last freeze of May 5 and 156 freeze-free days. Miami and Los Angeles stations record a 32°F freeze in fewer than half of years, so the median season is about 365 days. Start tomatoes indoors about 6 to 8 weeks before the median last freeze, and peppers about 8 to 10 weeks. Do not set frost-tender plants out until after that median date. The zone finder answers winter survival. This page answers the outdoor date.
Published · Updated
Example planting window
Planting window from the nearest listed NOAA station, New York, NY (NY CITY CNTRL PARK). The station is about 2.4 miles from this ZIP’s coordinate, so treat the dates as a regional estimate. This ZIP is USDA zone 7b (extreme low 5 to 10°F) on the 2023 map. Median last 32°F freeze: March 30. Median first 32°F freeze: November 20. Median freeze-free days: 236. A colder spring reaches 32°F about 1 year in 10 as late as April 9. An early fall reaches 32°F about 1 year in 10 by November 6. Start tomatoes indoors about 6 to 8 weeks before the median last 32°F date. Peppers often need 8 to 10 weeks. Do not set frost-tender plants outside until after that median date, and watch the later 10% spring date in a colder year.
What do sample cities show?
| City | Example ZIP | Zone | Extreme low | Median last 32°F | Median first 32°F | Freeze-free days |
|---|---|---|---|---|---|---|
| New York | 10008 | 7b | 5 to 10°F | March 30 | November 20 | 236 |
| Chicago | 60106 | 6a | -10 to -5°F | April 16 | October 28 | 193 |
| Minneapolis | 55450 | 5a | -20 to -15°F | April 23 | October 18 | 176 |
| Denver | 80019 | 6a | -10 to -5°F | May 5 | October 9 | 156 |
| Atlanta | 30337 | 8b | 15 to 20°F | March 15 | November 20 | 252 |
| Dallas | 75038 | 8b | 15 to 20°F | March 8 | November 24 | 262 |
| Seattle | 98148 | 9a | 20 to 25°F | March 2 | November 23 | 266 |
| Miami | 33152 | 11a | 40 to 45°F | Rarely 32°F | Rarely 32°F | 365 |
| Los Angeles | 90304 | 10b | 35 to 40°F | Rarely 32°F | Rarely 32°F | 365 |
| Boston | 02128 | 7a | 0 to 5°F | April 4 | November 9 | 218 |
Indoor start if the station has a last freeze: Start tomatoes indoors about 6 to 8 weeks before the median last 32°F date. Peppers often need 8 to 10 weeks. Do not set frost-tender plants outside until after that median date, and watch the later 10% spring date in a colder year. Use the date with tomatoes, strawberries, and flowers each season. Winter survival stays on the zone finder.
Common questions
Are these dates the coldest night I will get?+
No. The median last freeze is the middle of the historical record, so about half of springs are later. The 10% later date on the result is a colder spring, not a guarantee.
How is this different from the zone finder?+
The zone finder reports the 2023 extreme-low half-zone. This page reports calendar dates and freeze-free days from a weather station. Use the zone for “will it survive winter” and this page for “when can it go outside.”
What should I start indoors, and when?+
Start tomatoes about 6 to 8 weeks before the median last 32°F date, and peppers about 8 to 10 weeks. Where a station rarely reaches 32°F, a 4-week indoor start is enough for an earlier tomato.
What if the nearest station is far away?+
The result names the station and the distance. More than a short drive means a regional estimate. A mountain ZIP and a valley station do not share a frost date. Ask local Extension if the distance looks wrong.
Sources and notes
- NOAA NCEI: U.S. Climate Normals
- USDA Plant Hardiness Zone Map
- University of Maryland Extension: March gardening tips
Median dates are NOAA 1991–2020 32°F normals for 100 large-city stations, compiled by myplantingzone.com (CC BY 4.0, 2026-10-04) and matched here to the nearest station. Not a forecast. Sources checked November 4, 2026. Editorial responsibility.