Both ends of your growing season
Enter your ZIP code to see your estimated last and first frost dates, your frost-free season and USDA zone — and when summer heat usually arrives.
Free. No account or email. Built on NOAA 1991–2020 climate normals.
Cold nights, hot days —Frost dates, explained
Most frost date calculators stop at frost. Your plants feel the whole year: the last cold night of spring, the stretch of summer heat, and the first cold night of fall. Here’s what those dates mean, where they come from, and how to use them without trusting them too much.
Your last frost date is the typical date of the last 32°F night of late winter or spring. In this tool it is NOAA’s 50% date: in half of years the last freeze comes earlier, and in half it comes later.
That is why we also show a window. The later end is the 10% date — only about 1 year in 10 has a freeze after it — which is a more cautious target for frost-tender transplants such as tomatoes, peppers and basil.
Your first frost date is the typical date of the first 32°F night of fall or early winter — again NOAA’s 50% date. The earlier end of the window is the 10% date: about 1 year in 10 brings a freeze by then.
Gardeners use it to count backward when sowing fall crops (days to maturity) and to know when to have frost covers ready.
No. A USDA hardiness zone describes the average coldest winter night of the year (1991–2020), in 10°F zones split into 5°F halves. It helps you judge whether a perennial, shrub or tree can survive winter.
Zones do not say when the last spring frost or first fall frost usually happens. Two gardens in the same zone can have frost dates weeks apart, so this planner gets frost dates from NOAA station records and shows your zone separately.
Frost dates are probabilities from 30 years of history, not forecasts. Any given year can be earlier or later than the typical date, which is why the planner shows a range (the 90% to 10% dates) rather than a single “safe” day.
Accuracy also depends on how well the nearest NOAA station represents your garden. We show the station name and distance, and flag it when the station is far away or its winters look different from your ZIP’s USDA zone.
Cold air drains downhill and pools in low spots, so valleys and hollows can frost while nearby slopes do not. Elevation, distance from the coast or a large lake, paving, walls and tree cover can all shift frost and heat by days or weeks.
Frost can also form on plants when the official air temperature, measured about 6 feet above the ground, is 33–36°F. Treat your dates as a starting point and watch your local forecast.
Frost ends the season for tender plants, but heat can stall it. When highs reach 90°F or more and nights stay warm, tomatoes, peppers and other crops may drop blossoms and set less fruit. New transplants also lose water faster than their roots can replace it.
Knowing when heat usually arrives helps you plant early enough for roots to establish, plan shade and deep watering, and time fall sowings for when heat eases.
Use the typical last frost date to count back for indoor seed starting, and the cautious (10%) date before setting out frost-tender transplants. Use the typical first frost date to count back for fall crops, and have covers ready from the early end of the fall window.
Then let real conditions decide: check the 7–10 day forecast, soil temperature and the seed packet before you plant.
Enter your 5-digit ZIP above. The planner finds the nearest NOAA climate station with complete records and shows its typical (50%) last 32°F date, plus the range from the 90% to the 10% date. For frost-tender plants, the later 10% date is the more cautious target.
The first fall frost shown is NOAA’s 50% date for the first 32°F night at your nearest station. The early end of the window is the 10% date — about 1 year in 10 has a freeze by then — so it is a good time to have frost covers ready.
This planner uses 32°F, the National Weather Service freeze threshold and the standard NOAA frost-date threshold. Frost can still form on plants when the official air temperature is 33–36°F on clear, calm nights, especially in low spots.
Tools can use different stations, older 1981–2010 normals, other temperature thresholds (such as 28°F or 36°F), or other probability levels. Some estimate frost dates from USDA zones, which describe winter lows rather than frost timing. We show our station, threshold and probabilities so you can compare.
Where NOAA estimates less than a 1-in-10 chance of a 32°F night in a year, it does not calculate frost dates, and neither do we. The planner says frost is rare and focuses on heat instead. Where frost happens in some years but not most, the dates describe the years when it does freeze.
Heat Watch uses NOAA’s 1991–2020 average number of days per month with a high of 90°F or more at your station. Months averaging 10 or more such days are shown as your typical heat season; months with 3–9 days suggest occasional heat spells. It is a climate pattern, not a heat forecast, and we do not invent a single “heat date.”
No. It uses fixed NOAA climate normals and USDA zone data with transparent rules. Every note in “What this means for your garden” comes from those numbers. Check your local forecast before planting or covering plants.
Yes. Results and “Print my garden dates” are free with no account or email. An optional name personalizes the sheet and stays in your browser tab. Share and QR links contain only the NOAA station and USDA zone — never your name or ZIP.
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