When Is the First Freeze? Frost Dates by Zip Code

The first freeze of fall is the deadline for winterizing outdoor plumbing. Once the low reaches 32°F, the National Weather Service's definition of a freeze, hoses, outdoor faucets, and pipes exposed to outside air are the first at risk. Enter your zip code to see when that usually happens where you live: the typical first freeze, the first hard freeze (28°F), and the last freeze of spring, with the early and late dates, from NOAA's 1991–2020 U.S. Climate Normals for the nearest weather station.

How to Read Your Dates

NOAA gives each date as a probability, worked out from 30 years of nightly lows. Typical is the 50% date. In the fall, the first freeze comes on or before it in half of years. In the spring, half of years still have a freeze on or after it.

• The early fall date is the one to plan around. In 1 year in 10, the first 32°F night comes by then, so winterizing before it beats the first freeze in about 9 years out of 10. The late date is when the first freeze has come in 9 years in 10.
• The late spring date works the other way: 1 year in 10 still has a 32°F night on or after it.
• Freeze, hard freeze, and frost. The National Weather Service calls 32°F or below a freeze, and 28°F or lower for an extended period a hard freeze, the kind that kills most vegetation. Frost often forms with thermometer readings in the mid-30s.
• Warm climates. Where freezes don't come every year, NOAA's dates count only the years that have one, and NOAA gives no dates when fewer than 1 year in 10 has a freeze. The tool tells you how often a freeze comes before it gives the dates.
• Cold climates. At some northern and high-elevation stations, NOAA flags a risk of a freeze on any day of the year, so there's no frost-free season to plan around.

Winterize Before the First Freeze

Don't wait for the typical date: it's a coin flip. Finish the outdoor jobs before the early date, and the first freeze finds them done in about 9 years out of 10.

• Hoses and outdoor faucets. Disconnect and drain hoses. If an outdoor faucet has an inside shutoff valve, close it, then open the outdoor faucet so the line can drain. Our outdoor faucet guide covers frost-free faucets too.
• Sprinkler systems. Shut down and drain or blow out an in-ground system before the first hard freeze; see how to winterize a sprinkler system.
• The rest of fall. The fall checklist times furnace service, gutters, and air sealing to the same freeze, and the winter planner builds a checklist for your house.

As the date gets close, switch from averages to the forecast: our pipe-freeze check reads the National Weather Service hourly forecast for your zip code and says what to do before bed.

In Spring: After the Last Freeze

The spring dates tell you when it's safe to undo the winterizing. Our sprinkler guide says to turn an irrigation system back on after the last hard freeze, and the tool shows when the last 28°F night typically comes. Wait for the late date if you'd rather not risk it.

Why Your Yard Can Freeze Before the Station

A station's dates are a good guide for the area around it, but your yard can run colder. The National Weather Service measures temperature 5 feet above the ground, and cold air sinks. On clear, calm nights, the air near the ground can be several degrees colder than the station reads, so frost can form while the thermometer is above freezing, and valleys are the most likely places for it.

The University of Georgia Extension adds that cold air drains into low-lying areas and makes frost pockets, and that water, pavement, and city surroundings change how often frost forms. A tree or roof overhead keeps the spot under it warmer. So if your house sits low, or in the country near a city station, plan a little earlier. The result shows how far away the station is and how high it sits.

Where the Dates Come From

The dates are NOAA's 1991–2020 U.S. Climate Normals, the official 30-year normals its National Centers for Environmental Information (NCEI) produce every 10 years. The annual normals include frost and freeze dates for more than 7,300 stations with temperature records. NOAA computes them from each station's daily low temperatures, using 10,000 simulated years to smooth out the year-to-year swings.

For each zip code, the tool takes the Census Bureau's representative point for its ZIP Code Tabulation Area and picks the nearest station with freeze normals. The nearest station is 7 miles away for the median zip code. PO-box-only zip codes use the nearest residential zip code in the same area. These are long-term odds, not a forecast: a cold snap can come weeks early, or a mild fall weeks late.

Add This to Your Website

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<p style="font-size:14px">Frost dates by <a href="https://www.homeownerbasics.com/frost-dates-by-zip-code.html">Homeowner Basics</a>, from NOAA climate normals</p>

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Frequently Asked Questions

When is the first frost in my area?

Enter your zip code above. As examples from NOAA's normals, the first 32°F night typically comes by Oct 9 at Denver International Airport, Oct 29 at Milwaukee's Mitchell airport, and Nov 20 at Atlanta's Hartsfield-Jackson airport. Your nearest station may differ from the airport's.

What's the difference between frost and a freeze?

The National Weather Service calls a temperature of 32°F or below a freeze. Frost is ice crystals on surfaces, and it often forms when the thermometer reads in the mid-30s, because the ground can be colder than the air 5 feet up where temperatures are measured.

What is a hard freeze?

The National Weather Service defines a hard freeze as 28°F or lower for an extended period, cold enough to kill most vegetation. Our fall checklist and sprinkler guide use it as the deadline for draining irrigation lines.

Should I winterize by the average first-freeze date?

No. The typical date is when half of years have already had their first freeze. Finish outdoor plumbing by the early date the tool shows, and watch the forecast as it gets close.

Why does my zip code use a station in another town?

Only some weather stations have the long, complete records NOAA needs for freeze normals, so the tool uses the nearest one that does and tells you how far away it is. If it's far, or at a very different elevation, treat the dates as a rough guide.

How often are the dates updated?

NOAA's NCEI produces new official normals every 10 years. The 1991–2020 normals were first released in May 2021 and are the latest set.

The Bottom Line

Look up your zip code, and treat the early fall date as your winterizing deadline: hoses off, outdoor faucets drained, sprinklers blown out. When that date nears, check the real forecast with the pipe-freeze check. In spring, wait for the last hard freeze before turning outdoor water back on.

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