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First & Last Frost Dates by ZIP Code
Enter your ZIP code for your average first fall freeze and last spring freeze — from NOAA's long-term climate normals where a nearby station covers you, and a clearly-labeled USDA-zone approximation where one does not — plus the dates they actually set: when to overseed, when to winterize the sprinklers, when to expect the first freeze, and when it is safe to turn the irrigation back on. Free, no signup, and no email required to see the answer.
Free · no signup · NOAA 1991–2020 normals
Why your hardiness zone can't answer this
A USDA hardiness zone is the average annual extreme minimum temperature — how cold your winter gets at its worst. It says nothing about when the cold arrives, and the two come apart badly: Boise and New York City are both zone 7 — the same depth of winter cold — yet Boise's first freeze lands around October 15 and New York's around November 18, five weeks later, because one sits in high dry interior air and the other is held up by the Atlantic. Anything timed off a zone alone — an overseeding window, a winterization deadline — inherits that error.
So the dates above come from actual freeze observations: NOAA/NCEI 1991–2020 climate normals, specifically the 50th-percentile date of the first and last 32°F freeze at the nearest first-order station. Half of all years freeze earlier than the date shown. That is why every job the dates set is scheduled to finish before the date rather than to happen on it.
Typical frost dates by USDA zone
A rough national reference across every zone we model, useful when you want a feel for the spread rather than an answer for one address. Enter your ZIP above for the real one.
| USDA zone | First fall freeze | Last spring freeze | Climate |
|---|---|---|---|
| Zone 3 | September 15 | May 25 | very cold northern winters |
| Zone 4 | September 25 | May 15 | cold northern winters |
| Zone 5 | October 5 | May 5 | cold winters |
| Zone 6 | October 20 | April 22 | cool winters |
| Zone 7 | November 1 | April 5 | mild transition-zone winters |
| Zone 8 | November 15 | March 20 | mild Southern winters |
| Zone 9 | December 5 | February 20 | warm winters with only occasional frost |
| Zone 10 | December 28 | January 25 | warm winters with only rare frost |
Zone-level approximations only — these are the fallback the tool uses when a ZIP has no nearby station, and they are the roughest figures on this page. In zones 9 and 10 especially, many locations go whole years without reaching 32°F at all, so read those rows as “if it freezes, roughly then” rather than as an annual date.
Frequently asked questions
- What is a first frost date?
- It is the date by which, in a typical year, your area has had its first night at or below 32°F. The figures here are the 50th-percentile date from NOAA's 1991–2020 climate normals, which means half of all years freeze earlier than the date shown and half later.
- How accurate is a first frost date by ZIP code?
- It is a planning figure, not a forecast. Freeze dates scatter by roughly 12 days either side of the median at most US stations, and elevation, cold-air drainage and urban heat move the real date at a specific address. Use it to schedule the work; use the forecast to decide the day.
- Is a frost the same as a freeze?
- Not quite. Frost can form on surfaces at air temperatures slightly above freezing on a calm, clear night, and it damages tender plants. A freeze is the air itself at 32°F or below. A hard freeze — several hours below about 28°F — is the one that reaches buried irrigation pipe. The dates here are 32°F freeze dates.
- Can I use my USDA hardiness zone instead?
- No, and this is the single most common mistake in lawn-care advice. A hardiness zone is the average annual extreme minimum temperature — how cold it gets, not when. Boise and New York City are both zone 7, yet Boise freezes around October 15 and New York around November 18 — five weeks apart in the same zone. Anything timed off a zone alone can be weeks wrong.
- Where does this data come from?
- NOAA/NCEI 1991–2020 climate normals — specifically the 50th-percentile first and last 32°F freeze dates at each metro's nearest first-order station. If your ZIP is not covered by one of those stations, the answer falls back to a USDA-zone approximation, and the tool says so rather than presenting it as a station reading.
- Do I need to winterize my sprinklers if I only get a few freezes?
- It depends on how hard they get, and the tool answers it for your ZIP rather than in the abstract. Through USDA zone 8 the answer is usually yes: exposure is not proportional to how many freezes you get — one sustained hard freeze with a full backflow preventer is enough, and the repair costs the same whether it was the only cold night of the winter or the fortieth. Above zone 8 a 32°F night is common but the sustained hard freeze that cracks buried pipe is not, so a full blow-out is not standard practice — drain the backflow preventer and disconnect hoses before a cold snap instead. Your result above says which of those applies to you.