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Regional Calendars, Climate & DataEarly Fall Frost Risk Calendar
An early fall frost can end the season in a night. A fall frost risk calendar helps you plan plantings backward from the first frost and keep a harvest plan ready.
Key points
- Count back from the first frost using days to maturity plus a margin.
- Group crops by frost tolerance.
- Cover before sunset and watch the forecast.
- Use tested procedures for preserving the harvest.
What is a first fall frost date?
A first fall frost date is an average from past records, the point at which about half of years brought frost before it and half after. Some years frost comes weeks earlier, and some later. Treat the date as a midpoint and use a safety margin for important crops.
Check frost-probability tables from your extension office, or station data from NOAA National Centers for Environmental Information and the National Weather Service. Keep your own notes, because your site may differ from the station.
Pay attention to the first cold nights as signals. A clear, calm evening following a cool day can bring frost even when the nearest station reports a few degrees above freezing, so watch your own thermometer too.
How do you count back from the first frost?
Start with the days to maturity on the seed packet or in extension guides. Add extra days for slower growth as days shorten and nights cool, and count back from your first frost date to find the last practical planting date. If that date has passed, choose a faster variety, use transplants or protect the crop.
For example, if your average first fall frost falls in mid-October and a crop needs about two months to mature, you would count back at least that many days and then add margin. That is an illustration of the method and not a recommended date.
- Take days to maturity from a reliable source
- Add a margin for slow late-season growth
- Use transplants or faster varieties if time is short
Which crops tolerate fall frost?
Hardy crops such as kale, collards, spinach, carrots, beets and many brassicas handle light frost and often taste better after cool nights. Tender crops such as tomatoes, peppers, beans, squash and basil are damaged by frost, and a hard freeze kills them.
Ask your extension office for a frost-tolerance list for your crops, since tolerance varies by variety and stage. Mature fruit on a damaged plant can sometimes still be harvested, but quality varies.
Ripening can continue after a light frost for some fruit, but quality and yield vary. Check extension guidance for the crops you grow before relying on this.
How do you protect crops from the first frosts?
A first frost is often followed by weeks of mild weather, so covering for a few nights can extend the harvest. Use frost cloth or row cover, covering before sunset and letting it reach the ground. Remove it when temperatures rise.
Cold frames, low tunnels and high tunnels carry crops further into fall, though they need venting on sunny days and care with humidity. Watch the forecast, especially on clear, calm nights.
Keep covers, stakes and clips in one place so that you can cover quickly on short notice. A plan that is ready beats a plan that has to be built on the night of the frost.
When should you harvest before a hard frost?
If a hard freeze is forecast, harvest tender crops that can still be used, such as green tomatoes, peppers, squash and beans. Handle winter squash and pumpkins carefully and follow guidance for curing, and leave stems attached where recommended by extension.
For storing and preserving the harvest, use only tested procedures from the National Center for Home Food Preservation, USDA and extension. Never rely on untested recipes for canning, drying, fermenting or freezing.
Cure and store crops according to tested guidance, and sort out damaged produce for immediate use, since bruised or frost-damaged produce does not store well.
What about field crops and fall frost?
For field crops, frost before maturity can reduce yield and quality, depending on the crop and stage. Ask a crop adviser how to evaluate the damage and how it affects harvest timing, drying and storage.
Crop insurance and records matter in an early-frost year. Talk to your agent about reporting deadlines, and keep dated photos and notes of the frost and its effects. USDA RMA and FSA provide information on programs.
If you grow for sale, tell customers early if frost shortens your supply, and keep a list of dates and conditions for the next year's plan.
How do you build your fall frost calendar?
Write the average first frost date at the top of a sheet, then list each crop with its days to maturity and its last practical planting date. Add columns for frost tolerance and cover plans. Update the sheet after each fall with the actual frost date and results.
Over a few years the sheet becomes a calendar built on your own site, and your county extension office can help you adjust it.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.