At what temperature should I let faucets drip?

Start when your yard's overnight low drops toward 20°F. Exposed, uninsulated pipes begin to freeze around there, even though water freezes at 32°F. Plumbing inside insulated walls holds heat longer. Wind and how exposed the pipe sits move that number.

Do I need to drip faucets every cold night?

No. You need it on the nights your real low approaches the danger range for your most exposed pipe. A night that reads 34°F on the forecast rarely qualifies, unless your yard runs much colder than the forecast point.

How cold does it have to be for outdoor pipes to freeze?

An exposed or poorly insulated pipe can start freezing around 20°F. A sustained hard freeze matters more than a brief dip. A spigot on a warm wall survives colder nights than a line in an open crawlspace. The forecast low is a regional number, so your yard may sit colder.

August 7, 2026 · Updated September 12, 2026

How much of a drip keeps pipes from freezing

A stream about the width of a pencil lead keeps a pipe from freezing. You need it only on nights when your yard's real low drops toward 20°F. Moving water freezes slower, and an open faucet gives trapped pressure somewhere to go. The hard part is knowing which nights those are, because the forecast low is a regional number and your yard may run colder.

Why a trickle works

Water expands as it freezes, so a pipe bursts from pressure. Ice forms a plug. Water keeps arriving behind it. The pressure between the plug and a closed faucet climbs until the pipe fails. An open faucet lets that pressure escape, so the line holds even as a plug forms.

A moving stream also resists freezing longer than still water. It keeps bringing slightly warmer water past the cold spot. A pencil-lead trickle does both jobs at once. If the pipe carries hot and cold on a mixed line, crack both handles. Drip from the fixture farthest from where water enters the house.

How cold it has to be

Water freezes at 32°F. Plumbing inside a wall stays warmer than the outside air for hours. The exposed pipes fail first, like a spigot on a shaded wall, a line through an open crawlspace, or a run in an unheated garage. Those start to freeze near 20°F. A long hard freeze matters more than a brief dip to that number.

Wind pulls heat off a pipe faster than still air. A windy 24°F night can be worse than a calm 20°F one. Duration counts too. Two hours at 20°F rarely plugs a line. Ten hours can. A single cold reading tells you less than the shape of the whole night.

Which nights your yard dips that low

The forecast low describes a regional point, often an airport. Your yard can sit several degrees off it. Cold air is denser than warm air. When the wind dies, that dense air slides down the slope and settles into the lowest ground. A yard at the bottom of a slope can read well below the number on your phone. Fences that box in the air do the same. That gap decides whether a 26°F forecast is a drip night for you.

On cold nights our own station reads about 7°F below the forecast. Our coldest night this year dropped to 3°F. A forecast of 27°F on that pattern lands near 20°F in the yard. That is a drip night for an exposed spigot. A yard that runs warmer than its forecast would skip it. You cannot know your own gap without measuring it against the same night's forecast.

You can find that gap two ways. Type a manual offset into Settings after you watch a few cold nights. The free tier then applies it to your frost alerts. Or connect a weather station. It learns the offset for you after about 14 overlapping nights, then adjusts your alerts on its own. Both let a freeze warning speak to your yard instead of the region. Our companion guide on the nights your pipes are at risk walks the same logic for outdoor plumbing.

If you drip a faucet, keep that drain from icing over. Shut off and drain any dedicated outdoor spigot line before the first hard freeze. A dripping tap over a frozen drain backs up.

The yard low tells you the risk in the open air. It cannot see whether a pipe is insulated, buried below the frost line, or tucked against a heated wall. Treat the coldest, most exposed run as your trigger. Before you build your own record, the microclimate comparison estimates how far your area usually sits below its forecast. Then connect a station to pin down your own yard after a few cold nights.

Common questions.

How much of a drip keeps pipes from freezing?: A stream about the width of a pencil lead is enough. Moving water relieves the pressure that bursts pipes, and an open faucet gives that pressure somewhere to go. If the line at risk carries both hot and cold, crack both handles a touch.
At what temperature should I let faucets drip?: Start when your yard's overnight low drops toward 20°F. Exposed, uninsulated pipes begin to freeze around there, even though water freezes at 32°F. Plumbing inside insulated walls holds heat longer. Wind and how exposed the pipe sits move that number.
Do I need to drip faucets every cold night?: No. You need it on the nights your real low approaches the danger range for your most exposed pipe. A night that reads 34°F on the forecast rarely qualifies, unless your yard runs much colder than the forecast point.
How cold does it have to be for outdoor pipes to freeze?: An exposed or poorly insulated pipe can start freezing around 20°F. A sustained hard freeze matters more than a brief dip. A spigot on a warm wall survives colder nights than a line in an open crawlspace. The forecast low is a regional number, so your yard may sit colder.

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