How Cold Is Too Cold in a House With No Heat?
If the heat's out, don't wait for one magic number to decide whether the house is safe. There's no universal indoor temperature that protects every person in every home. The CDC notes that hypothermia can happen even above 40°F when a person becomes chilled, and the National Weather Service says it can occur in some circumstances at temperatures as warm as 60°F. CDC hypothermia guidance and National Weather Service cold-weather guidance can help you recognize the risk.
There's a second problem to manage: your plumbing. The often-cited 55°F setting is guidance for cutting frozen-pipe risk when a home's unoccupied. It's not a medical safety guarantee for people living in a house with no heat. Move anyone who's confused, unusually sleepy, exhausted, or unable to stop shivering to a warm place and get medical help, then call us about the heating failure.
What to do as a no-heat home gets colder
| What you notice | The safer next move |
|---|---|
| Someone is shivering, confused, drowsy, or exhausted | Move them to a warm, dry shelter and arrange medical help |
| The indoor temperature keeps falling | Close off unused rooms, use safe temporary heat, and arrange diagnosis |
| Pipes run through an exterior wall or unheated space | Open sink cabinets, monitor the plumbing, and locate the water shutoff |
| A faucet gives only a trickle or water appears near a pipe | Treat it as possible frozen or burst plumbing and contact a plumber |
| There is gas odor, smoke, fire, sparking, or a CO alarm | Leave immediately and call 911 or the utility from outside |
What temperature is too cold for people
A thermostat reading describes the room, not the condition of the people in it. A healthy adult in dry layers may tolerate a cool room for a limited stretch, while a baby, older adult, or person with a health condition can become vulnerable sooner. Wet clothing, drafts, exhaustion, alcohol, and a long outage can make the same indoor temperature more dangerous.
Watch the people in the house instead of using the thermostat as the only test. The CDC lists shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech, and drowsiness as warning signs of hypothermia. A body temperature below 95°F needs immediate medical attention. If someone has those symptoms, get them into a warm, dry shelter, remove wet clothing, warm the center of the body with dry layers and blankets, and get medical help. Review the CDC warning signs before a winter outage gets harder to manage.
Don't leave an infant, older adult, or medically vulnerable person in a cold house just because the thermostat still reads above freezing. A winter storm can also isolate a household while heat and power stay out, so make a backup plan before the home's hard to leave. National Weather Service winter preparedness guidance includes planning for that.
- Move vulnerable people to reliable warmth before they become hard to warm up.
- Treat confusion, unusual sleepiness, exhaustion, and uncontrolled shivering as medical warning signs.
- Don't use the freezing point of water as a safe living-temperature test.
Is 55°F safe when the heat is off
Think of 55°F as a plumbing-protection reference, not a universal indoor-health threshold. The American Red Cross recommends leaving heat set no lower than 55°F when you're away during cold weather. That advice is meant to cut the chance of frozen pipes. It doesn't mean every person is safe in a 55°F home, and it doesn't guarantee pipes won't freeze in an exposed crawlspace, garage, attic, or exterior wall. See the Red Cross frozen-pipe guidance.
If people are staying in the house, focus first on human warmth and a safe place to sleep. If the home will be empty, keeping the indoor temperature at or above the pipe-protection guidance, opening doors beneath sinks, and arranging a property check can cut risk. A vacant home may need a different plan if pipes run through unheated spaces.
Don't confuse the freezing point of water with a safe living temperature. Water can freeze in a cold spot before the main living area reaches 32°F. Meanwhile, a room can stay uncomfortable and medically risky well above that point for someone who's wet, exhausted, very young, older, or ill.
- Use 55°F as a starting point for cutting pipe risk in an empty home, not as a promise of human safety.
- If anyone is staying there, judge safety by their condition and access to reliable warmth.
- Arrange a property check when a vacant home has vulnerable plumbing or unheated areas.
How cold is too cold for pipes
Pipes are most exposed where the house doesn't circulate warm air well. The National Weather Service names plumbing on exterior walls and in basements, attics, and under kitchen cabinets as common freezing spots. When water freezes, it expands, which can burst a pipe and release water once the ice starts to thaw. Read the National Weather Service frozen-pipe guidance.
While you're waiting on us for the heating repair, open kitchen and bathroom cabinet doors so warmer room air can reach the plumbing, keeping cleaners and chemicals away from children first. Keep garage doors closed if water lines run through the garage. If your water utility or plumber has told you to do so, allow a small flow from a faucet serving an exposed pipe. That's not a substitute for restoring heat. Know where the main water shutoff is before a leak starts.
If a faucet gives only a trickle, or you see water around a pipe, treat it as a possible frozen or burst-pipe problem. Avoid turning the water back on quickly after thawing if you can't inspect for leaks. Never use a torch, open flame, charcoal stove, kerosene heater, or propane heater to thaw a pipe. If a pipe's burst, the frozen section's inaccessible, or water's spreading through the home, shut off water if you can do so safely and call a plumber.
- Open cabinets beneath sinks on exterior walls after moving hazardous cleaners out of children's reach.
- Locate the main water shutoff before a frozen pipe becomes a leak.
- Never thaw plumbing with an open flame or fuel-burning heater.
What can you do while waiting for heat
Start with heat retention. Close off rooms no one needs, place towels or spare clothing at door gaps, and cover windows at night. Wear dry layers, a hat, socks, and blankets. Eat and drink normally, and skip alcohol as a way to feel warm. The National Weather Service recommends closing off unneeded rooms and blocking drafts during a no-heat winter outage.
An electric space heater can add risk if it's placed or powered wrong. If you use an approved heater, keep it at least 3 feet from curtains, bedding, furniture, and other combustible materials. Plug it directly into a wall outlet, never an extension cord or power strip, and turn it off when people sleep. Don't leave it running unattended. Follow CPSC space-heater safety guidance.
Never use a gas range, oven, grill, outdoor heater, charcoal appliance, or generator to heat the house. A generator belongs outdoors and away from the home, not in a basement, garage, porch, or doorway. Fuel-burning equipment can produce carbon monoxide, which has no smell or color. If a CO alarm sounds, or anyone has a headache, dizziness, weakness, nausea, confusion, or unusual sleepiness while fuel-burning equipment's running, leave for fresh air right away and call 911 from outside or from a neighbor's home. Review CPSC carbon-monoxide guidance.
- Keep approved electric heaters 3 feet from anything that can burn, and plug them directly into a wall outlet.
- Never use an oven, grill, charcoal appliance, or generator as an indoor heat source.
- Leave immediately if a CO alarm sounds or fuel-burning equipment causes symptoms.
When should you call for HVAC diagnosis
Once everyone's safe, make only the checks that don't require opening the equipment. Confirm the thermostat's set to heat, the desired temperature's above the room temperature, and the system has power. If a breaker's tripped, one careful reset may be reasonable if there's no burning smell, water, smoke, or other danger. A breaker that trips again is a stop sign, not an invitation to keep resetting it.
Call us when the furnace or heat pump still isn't producing heat, the thermostat's blank, the system starts and stops without warming the house, airflow's weak, or the home keeps getting colder. Tell us what changed, what the thermostat displays, whether the system makes any sound, and whether you noticed water, ice, an odor, or a tripped breaker. Those observations are more useful to us than a guess at which part failed.
For a Frederick County homeowner, the right next step is usually calling us once the household and plumbing risks are under control. We find the actual fault, then talk through whether repair, maintenance, or replacement makes sense for the equipment and the home. If there's a gas odor, smoke, a CO alarm, or an immediate health concern, handle that emergency first and call 911.
- Check the thermostat and system power once, only when there's no immediate hazard.
- Report the system type, recent change, sounds, airflow, water, ice, odors, and breaker behavior.
- Don't open sealed panels, bypass safety controls, or troubleshoot gas and electrical components.
Questions that come up next
Is 40°F indoors automatically dangerous?
It's a serious warning, but not a complete medical test. Hypothermia can occur above 40°F when someone becomes chilled, so watch for symptoms and move vulnerable people to warmth.
Can I leave my home at 55°F overnight?
The 55°F guidance is commonly used to cut frozen-pipe risk in an unoccupied home, but it's not a guarantee for every plumbing layout or a universal safe temperature for every person. If anyone's staying there, judge safety by their condition and access to reliable warmth.
What if the house is cold but the pipes are not frozen?
You still need to protect people from prolonged cold exposure and get the heat back. Check the thermostat and power once, use only safe temporary warming, and call us if the system doesn't recover.
Should I use the oven to warm the room?
No. The CPSC warns against using gas ranges or ovens to heat a home because fuel-burning appliances can create carbon monoxide. Use approved equipment per its instructions.
How long can a house stay without heat?
There's no safe universal time limit. The answer changes with outdoor weather, insulation, pipe locations, occupants, clothing, health, and whether a safe heat source is available. Treat a falling indoor temperature as a problem to solve now, not a timer to test.
Need HVAC help in Frederick?
Tell us what the system is doing and what you've checked already. If it needs a visit, we'll say so.