A freeze alarm texts or alerts you when the house gets cold, so you can act before a pipe freezes. For most empty homes, a Wi-Fi sensor with text alerts and no subscription, like the Temp Stick, is the one to buy. For leak detection too, Moen’s Flo Smart Leak Detector, which also alerts on room temperature. For a well house or detached building, a long-range YoLink kit.
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Our pick: the Temp Stick Wi-Fi sensor, with text alerts and no subscription. Check the Temp Stick on Amazon
In an empty house, the danger is something going wrong while nobody is home: the furnace quits, the power goes out, or a thermostat gets turned down too far. A freeze alarm is the simplest way to find out while there is still time to do something about it. It watches the temperature and alerts your phone when it drops past a point you choose, hours before the water in the pipes turns to ice. The three picks below were sold or shipped by Amazon, new and in stock, when we checked: the Temp Stick and YoLink on September 23, 2026, and the Moen detector on October 3, 2026.
Freeze Alarms Compared
| Alarm | Best for | How it alerts |
|---|---|---|
| Temp Stick | Best Overall | Wi-Fi, no hub · text, app and email · your own trigger |
| Moen Flo leak detector | Best Leak and Freeze Combo | Wi-Fi · app alerts · temperature point you set · also detects leaks |
| YoLink kit | Best for Outbuildings | LoRa radio + hub · app · your own trigger |
Every spec above comes from the product’s Amazon listing as read on September 23, 2026.
Best OverallEditor’s Choice
Temp Stick Remote WiFi Temperature and Humidity Sensor
Wi-Fi, no hub · no subscription · text, app and email alerts · runs on 2 AA batteries for 1–2 years · stores readings while offline and uploads up to a month on reconnect · made in the USA (all per the listing)
Check the Temp Stick on Amazon →
The Temp Stick is the one to buy when the point is a text message reaching you while the house is empty. The listing says it connects straight to your Wi-Fi with no hub, needs no subscription, and sends text, app and email alerts, which matters at 3 a.m. when an app notification is easy to sleep through. It runs on two AA batteries for one to two years according to the listing, and if the Wi-Fi drops it keeps logging and uploads up to a month of stored readings when it reconnects, so you can see afterward how cold the house got.
- Text, app and email alerts with no subscription, per the listing.
- Connects to Wi-Fi directly, with no hub to power or place.
- Keeps logging during a Wi-Fi outage and uploads the stored readings afterward.
- Works on 2.4 GHz Wi-Fi only, not guest or public networks (per the listing).
- Temperature and humidity only; it does not detect a leak.
- Alerts still depend on the house’s Wi-Fi and power being up (see below).
Verdict: Best for a second home, a snowbird house or a rental where you need a text the moment the heat quits.
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Best Leak and Freeze in One
Moen Flo Smart Leak Detector (920-004)
Wi-Fi (2.4 GHz) · senses water at the base or at a 48-inch remote sensing disc · app alerts for moisture, humidity and room temperature · CR123A battery Moen rates at up to 2 years · 1-year warranty (all per Moen’s spec sheet)
Check the Moen Flo Smart Leak Detector on Amazon →
Moen’s detector does two jobs from one spot on the floor. Moen’s spec sheet says it monitors moisture, humidity and room temperature, with app alerts you can set for room temperature anywhere from 0 to 140°F, so you choose the warning point. It senses water at its base or at a 48-inch remote sensing disc that can sit in a low, hard-to-reach spot, runs on a CR123A lithium battery Moen says lasts up to two years, and needs a 2.4 GHz Wi-Fi network. If a Moen Flo shutoff is ever fitted on the main, Moen says the detector can trigger it to close. Put one where a freeze and a leak are both likely — a crawl-space entry, a basement wall, a garage utility corner — and it covers both failures. (We used to link a Kidde leak and freeze alarm here; on 10/3/2026 its Amazon listing was sold by a third-party seller, not by Amazon or the maker.)
- Leak detection and a temperature alert in one battery sensor.
- You set the temperature alert point, from 0 to 140°F, per Moen’s spec sheet.
- Can trigger a Moen Flo shutoff if one is installed, per Moen.
- Alerts come through Moen’s app; the spec sheet does not mention text messages.
- Needs 2.4 GHz Wi-Fi, so it cannot reach you if the router or power is down.
- 1-year warranty, per Moen.
Verdict: Best for a spot where a leak and a freeze are equally likely.
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Best for Outbuildings and Long Range
YoLink Temperature and Humidity Sensor Kit (Sensor + Hub)
LoRa radio, up to 2,034 ft open-air range · sensor plus hub · hub connects to the router by Ethernet · high and low set-point alerts · works with Alexa and IFTTT · years between battery changes (all per the listing)
Check the YoLink sensor and hub kit on Amazon →
Wi-Fi rarely reaches a well house, a detached garage, a barn or the far end of a crawl space. YoLink’s sensors use LoRa radio instead, and the listing claims up to 2,034 feet of range in open air, plus operation outdoors, on other floors and even inside a metal box. The kit includes the hub, which plugs into your router by Ethernet, and the app alerts you when the temperature crosses the high or low point you set. Add more YoLink sensors to the same hub as you find more cold spots.
- LoRa range up to 2,034 ft open-air, per the listing, for buildings Wi-Fi does not reach.
- Set your own low-temperature alert point.
- One hub runs more sensors as you add them.
- Needs the hub plugged into your router; no hub, no alerts.
- The kit is one sensor; each additional spot is another sensor.
Verdict: Best for well houses, detached garages, barns and big crawl spaces beyond Wi-Fi range.
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The Weak Spot: Power and Internet
Every alarm on this page reaches you through your home internet. The sensors run on batteries, but the router and modem do not, so the same power outage that stops the furnace can stop the alert. Two things close most of that gap: a small battery backup on the router and modem, and a neighbor with a key who knows to check the house if you lose contact with the sensor. Landline and cellular dialer freeze alarms also exist; none we checked was sold new and in stock by Amazon on September 23, 2026, so they are not picked here.
Set the Alert Where It Buys You Time
The American Red Cross advises that if you are going away in cold weather you leave the heat on, set no lower than 55°F. Set the alarm’s low point below your thermostat setting but well above freezing, so the alert means the heat has stopped keeping up, not that the pipes are already freezing. That leaves time for a neighbor or a service call. When an alert comes and nobody can get there, the fallback is to have someone shut off the main and open the faucets; see how to shut off your water main.
Where to Put the Sensor
Put the sensor next to the pipes most likely to freeze, not in the living room. The Red Cross lists the pipes that freeze most often: outdoor hose bibs, supply pipes in unheated basements, crawl spaces, attics, garages and kitchen cabinets, and pipes that run against exterior walls with little insulation. A kitchen sink cabinet on an outside wall, the crawl-space entry and an attached garage are the usual first choices. Then protect those same pipes: pipe insulation for the exposed runs and heat tape for the one that freezes every year.
FAQ
What temperature should a freeze alarm be set to?
Well above 32°F, so you have time to act. The American Red Cross advises leaving the heat set no lower than 55°F when you are away in cold weather; an alert a few degrees below that setting tells you the heat has stopped keeping up while the pipes are still safe. The Temp Stick, the YoLink and the Moen detector all let you choose the point.
Where should I put a freeze alarm?
Next to the pipes most likely to freeze, not in the warmest room. The Red Cross names pipes in unheated basements, crawl spaces, attics, garages and kitchen cabinets, and pipes against exterior walls with little insulation. A sensor at the coldest spot on that list warns you first.
Will a Wi-Fi freeze alarm work if the power goes out?
The sensor may keep running on its batteries, but your router needs power to send the alert, so a power outage can silence it at the worst moment. Plan for it: a battery backup on the router and modem, and a neighbor who can check the house if an alert stops arriving.
Is a freeze alarm the same as a water leak detector?
No. A leak detector tells you water is already on the floor; a freeze alarm tells you the house is getting cold before a pipe splits. Moen’s Flo Smart Leak Detector does both. For leak sensing across the house, see our water leak detector picks.
Why Trust Plumbing Picks
Plumbing Picks is written by a Journeyman Plumber — State of Georgia Licence #JP507711 — and the license is verifiable through the Georgia Secretary of State’s license verification portal. Nobody pays to be included here and no manufacturer sponsors the site. The picks on this page were chosen from what Amazon itself sold or shipped, new and in stock, when we checked on September 23, 2026 (the Moen detector on October 3, 2026), and every product detail comes from the listing or the maker, not from hands-on testing. Where a link goes to Amazon we may earn a commission at no extra cost to you. More on who writes this and how we pick.
Bottom Line
Buy the Temp Stick if you need a text message the moment an empty house gets cold. Buy the Moen Flo Smart Leak Detector if you want a temperature alert and a leak alarm in the same sensor. Buy the YoLink kit for a well house, barn or detached garage that Wi-Fi does not reach. Put the sensor by the coldest pipes, set it well above freezing, and give your router a battery backup so the alert can still get out when the power fails. If you are leaving the house for the season, work through the winterizing checklist too.
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