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Freeze data
When do pipes freeze?
The short answer
Pipes come under threat on the first night that gets well below freezing, and that date is on the record for wherever you live. Across the 6,948 US weather stations that publish 1991 to 2020 normals, the median first 32°F night runs from early September in interior Alaska to mid-January on the Florida peninsula. The dates that matter more for plumbing are the first 28°F and first 20°F nights, which arrive weeks after the first light frost. Enter a ZIP code below for all three at the nearest station, with the spread: the date one year in ten beats, and the date nine years in ten beat.
When does the first freeze arrive at your ZIP?
Ten cities
First freeze in the cities we cover
The nearest reporting station to each city centre, with the median date each threshold is first crossed.
| City | First 32°F | First 28°F | First 20°F | Last 32°F | Nights below 20°F |
|---|---|---|---|---|---|
| Omaha, NEOMAHA EPPLEY AIRFIELD | October 21 | October 30 | November 17 | April 18 | 61 |
| Des Moines, IADES MOINES INTL AP | October 20 | October 30 | November 14 | April 18 | 59 |
| Kansas City, MOKANSAS CITY DOWNTOWN AP | November 2 | November 11 | November 29 | April 4 | 31 |
| Oklahoma City, OKOKLAHOMA CITY WILL ROGERS AP | November 2 | November 11 | December 3 | April 4 | 15 |
| Fort Worth, TXFT WORTH MEACHAM FLD NAAF | November 24 | December 6 | January 5 | March 5 | 3.1 |
| Austin, TXAUSTIN 6S | November 17 | December 1 | January 4 | March 10 | 1.3 |
| San Antonio, TXSAN ANTONIO INCARNATE WORD | November 28 | December 15 | January 6 | February 25 | 0.5 |
| Las Vegas, NVN LAS VEGAS | December 8 | December 21 | no normal | February 1 | 0 |
| Jacksonville, FLJACKSONVILLE NAS | January 5 | January 14 | no normal | February 1 | 0 |
| Tampa, FLTAMPA INTL AP | January 12 | no normal | no normal | January 20 | 0 |
Dates are the median: half of years cross that threshold earlier, half later. “no normal” means NOAA publishes none for that station, which at a warm station means it does not reliably get that cold. Source: NOAA NCEI U.S. Climate Normals, 1991-2020, retrieved 2026-09-09.
The spread across ten cities is most of the story of American plumbing risk. Des Moines crosses 20°F for the first time around November 14 and then does it another 59 nights in an average year. Tampa has never recorded enough 20°F nights for NOAA to publish a normal for one, and averages 0.8 nights below freezing a year. Those two places need different winter plumbing, and the same national advice is written for both of them.
Our rule
The winterize-by date
One date to drain hose bibs, blow out irrigation, and disconnect hoses.
The first light frost is a poor trigger for winterizing, because it usually passes without hurting anything, and the first hard freeze is a poor trigger too, because by then you are already exposed. So we use a third date and we are explicit that it is ours rather than anyone else’s: the date by which one year in ten has already hit 28°F. In NOAA’s terms that is the 10th percentile first-28°F date, and it means that if you winterize by it, you were early in nine winters out of ten.
For Kansas City that date is October 28, about a week before the median first freeze of any kind. For Des Moines it is October 16. Your ZIP code’s figure is in the checker above, in the 1-year-in-10 column of the 28°F row.
Two limits worth stating. The rule uses 1991 to 2020 normals, so it describes a typical recent winter rather than the winter ahead. And it says nothing about how cold that night gets, only when the first one tends to land. For the temperature side, see at what temperature pipes actually freeze.
All 50 states
First freeze by state
Median dates across every station in the state that publishes the normal.
| State | Median first 32°F | Median first 20°F | Median last 32°F | Nights below 20°F | Stations |
|---|---|---|---|---|---|
| Alabama | November 9 | December 30 | March 21 | 6 | 118 |
| Alaska | September 22 | October 23 | May 16 | 103 | 163 |
| Arizona | November 12 | December 4 | March 29 | 3.6 | 174 |
| Arkansas | November 6 | December 18 | March 27 | 11 | 112 |
| California | December 1 | December 21 | February 25 | 0.1 | 332 |
| Colorado | October 4 | October 31 | May 11 | 84 | 210 |
| Connecticut | October 17 | November 25 | April 25 | 47 | 23 |
| Delaware | November 4 | December 15 | April 7 | 21 | 7 |
| Florida | January 6 | January 11 | February 1 | 0 | 139 |
| Georgia | November 12 | January 2 | March 21 | 3.9 | 126 |
| Hawaii | December 1 | no normal | January 26 | 0 | 2 |
| Idaho | September 29 | November 4 | May 16 | 58 | 127 |
| Illinois | October 21 | November 21 | April 18 | 49 | 170 |
| Indiana | October 21 | November 24 | April 21 | 45 | 117 |
| Iowa | October 10 | November 7 | April 28 | 77 | 150 |
| Kansas | October 20 | November 16 | April 19 | 49 | 176 |
| Kentucky | October 25 | November 28 | April 15 | 28 | 97 |
| Louisiana | November 24 | January 7 | March 1 | 0.9 | 98 |
| Maine | October 2 | November 9 | May 8 | 93 | 82 |
| Maryland | November 2 | December 15 | April 8 | 21 | 43 |
| Massachusetts | October 14 | November 21 | April 27 | 52 | 69 |
| Michigan | October 11 | November 18 | May 8 | 69 | 211 |
| Minnesota | October 2 | November 2 | May 5 | 104 | 179 |
| Mississippi | November 11 | January 1 | March 16 | 4.9 | 94 |
| Missouri | October 24 | November 24 | April 12 | 38 | 171 |
| Montana | September 21 | October 20 | May 20 | 91 | 216 |
| Nebraska | October 7 | November 3 | May 2 | 79 | 184 |
| Nevada | October 4 | November 2 | May 12 | 58 | 109 |
| New Hampshire | October 4 | November 11 | May 8 | 82 | 54 |
| New Jersey | October 27 | December 2 | April 16 | 33 | 48 |
| New Mexico | October 17 | November 14 | April 29 | 49 | 175 |
| New York | October 12 | November 18 | May 4 | 66 | 176 |
| North Carolina | November 4 | December 20 | April 1 | 10 | 187 |
| North Dakota | September 27 | October 24 | May 13 | 116 | 125 |
| Ohio | October 22 | November 24 | April 24 | 46 | 130 |
| Oklahoma | November 1 | December 1 | April 5 | 20 | 193 |
| Oregon | October 22 | December 7 | April 22 | 4 | 172 |
| Pennsylvania | October 19 | November 23 | April 28 | 47 | 160 |
| Rhode Island | October 20 | November 27 | April 22 | 43 | 11 |
| South Carolina | November 9 | January 1 | March 26 | 5.3 | 103 |
| South Dakota | October 1 | October 29 | May 8 | 97 | 166 |
| Tennessee | October 29 | December 2 | April 7 | 20 | 148 |
| Texas | November 16 | December 27 | March 14 | 3.3 | 476 |
| Utah | October 5 | November 6 | May 11 | 68 | 169 |
| Vermont | October 1 | November 5 | May 13 | 89 | 45 |
| Virginia | October 28 | December 2 | April 14 | 24 | 125 |
| Washington | October 20 | December 8 | April 22 | 11 | 154 |
| West Virginia | October 20 | November 21 | April 26 | 41 | 99 |
| Wisconsin | October 6 | November 10 | May 5 | 86 | 204 |
| Wyoming | September 24 | October 23 | May 20 | 97 | 129 |
Each row is the median across every station in that state with a published normal, so a state with one climate zone reads cleanly and a state with several reads as a middle. Hawaii is the extreme case: its two stations are both mountain observatories, which is why it has a freeze date at all. Source: NOAA NCEI U.S. Climate Normals, 1991 to 2020, retrieved 2026-09-09.
What it means
What this means for your pipes
A first-freeze date is a planning number. It tells you when to drain the outside spigots and put a foam sleeve on the run through the crawl space, and it tells you roughly how many nights of exposure a winter holds. It does not tell you that a pipe will freeze on that date.
The practical sequence is short. Learn which temperature matters and how many nights a year your ZIP crosses it. Do the winterizing by the date above. Then, if a faucet does go quiet in a cold snap, work through what to do about a frozen pipe before it splits, because the repair after a burst and the water damage behind it are the expensive part.
If you are digging rather than thawing, the companion number is depth: how far down the ground itself freezes where you live, on our frost line depth page.
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Common questions
First freeze questions
At what house temperature do pipes freeze?
Indoor air is not what freezes a pipe. What matters is the temperature in the unheated space the pipe runs through: an attic, a crawl space, an exterior wall cavity, an unheated garage. Those spaces track outdoor air far more closely than they track your thermostat, which is why guidance for a cold snap is to keep the house at 55°F or higher and open cabinet doors so heated air can reach the pipes behind them. A pipe in a heated room is not the one that bursts.
How will I know if my pipes froze?
The first sign is almost always flow. A faucet that opens to a trickle or to nothing, while other fixtures run normally, points at a frozen section upstream of it. Frost or bulging on an exposed pipe, and a smell of sewage from a drain that has stopped moving, are the other two. If you find one, open that faucet before you do anything else so melting water has somewhere to go.
How long does it take pipes to freeze at 30 degrees?
No authority publishes a reliable hours-to-freeze figure, and we will not invent one. The time depends on the pipe material and diameter, how much insulation sits around it, whether water is moving, how windy it is, and how cold the space actually gets rather than what the thermometer outside reads. What the record does support is a threshold: at 30°F a pipe in a heated house is rarely at risk, while a long night in the low 20s in an unheated space is where burst calls come from.
Does the first freeze of the year mean my pipes are at risk?
Usually not on its own. The median first 32°F night is a light freeze, often an hour or two before dawn, and an insulated pipe inside a heated house rides it out. The dates worth marking are the first 28°F and first 20°F nights, which arrive weeks later in most of the country and are the ones associated with burst risk. Both are in the table above for your station.
When should I winterize outdoor faucets and irrigation?
Ahead of the first hard freeze, not the first frost. We use the date by which one year in ten has already hit 28°F, which for Des Moines is October 16 and for Kansas City is October 28. That is our rule rather than a code requirement, and it is deliberately early: the cost of draining a hose bib a few weeks too soon is nothing next to a split line.
Where these numbers come from
Every date on this page is a NOAA normal, not our estimate. A “median first 32°F” is the date by which half of the winters in the 1991 to 2020 record had already seen a 32°F night at that station. Where a station has no published normal for a threshold, the table says so instead of showing a zero, because at a warm station the absence is the finding.
- Freeze dates and cold-night counts: NOAA NCEI U.S. Climate Normals, 1991 to 2020, annual and seasonal by station. Retrieved 2026-09-09. Field definitions are in the by-variable readme.
- ZIP code locations: U.S. Census Bureau 2023 ZIP Code Tabulation Area gazetteer, matched to the nearest station by great-circle distance.
The full method, including how we pick a station and what we do when there is not one close enough, is on our methodology page.
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