How to respond to a carbon monoxide alarm during a winter power outage at night

Short answer

Why people ask this

Because it’s night during a winter outage, people worry about getting cold if they evacuate and whether it’s safe to wait inside. Darkness can make it hard to verify the alarm type, and snow or ice may complicate getting out or finding warm shelter. Folks also wonder if briefly opening windows in subfreezing weather is enough, and whether running a car or generator can keep them warm without risk. Confusion between a continuous CO alarm and an occasional low-battery chirp is common when power is out.

When it might be safe

• If the device is chirping intermittently (e.g., every 30–60 seconds), indicating low battery, not a continuous CO alarm—confirm with the manual or label using a flashlight.
• If you can quickly silence and reset the unit, then test a second CO alarm to cross-check readings before reentering.
• If everyone is symptom-free and you’ve already moved to fresh air, you can ventilate the home briefly (even in freezing temps) and await responders.

When it is not safe

• Running a generator in a garage, on a porch, or near doors/windows during the outage—even with the door open—CO can enter the home.
• Using a gas oven, stove, or charcoal/propane grill for heat at night; these can rapidly produce CO indoors.
• Idling a vehicle in an attached garage or near the house for warmth; snow can block the tailpipe and push CO into the car and home.
• Reentering the home before it’s cleared by professionals, especially if snow may be blocking exterior vents or flues.
• Ignoring a continuous alarm because it’s cold outside or assuming it’s a false alarm.

Possible risks

• Carbon monoxide poisoning: headache, dizziness, nausea, confusion, or sleepiness that can progress to loss of consciousness.
• Worsening CO buildup overnight due to snow-blocked vents, sealed windows, and use of emergency heat sources.
• Hypothermia while evacuating in freezing, windy conditions at night if you don’t plan warm shelter promptly.
• Relapse exposure by using a car or generator for heat too close to the home or with a blocked tailpipe.
• False reassurance from silencing the alarm without addressing the source or getting fresh air.

Safer alternatives

• Evacuate to fresh air immediately, call 911, and wait in a safe warm location: a neighbor’s home, a running car parked fully outdoors with the tailpipe cleared of snow and pointed away from buildings, or an open overnight warming center.
• If it’s safe to do so quickly, open doors/windows for a few minutes to ventilate despite the cold, then close up and stay outside or in a safe alternate shelter.
• Turn off potential CO sources if accessible on the way out (gas appliances, portable heaters), and keep generators 20+ feet from the home, downwind.
• Carry emergency cold-weather kits by the exit: coats, boots, blankets, hats, and a flashlight or headlamp for nighttime evacuation.
• Use multiple battery-powered CO alarms (or a plug-in with battery backup) to cross-check and place one near sleeping areas for faster night detection.

Bottom line

Treat any CO alarm as real: get everyone to fresh air, call 911, and seek safe warmth away from the home. In a winter nighttime outage, avoid generators or vehicles near the house, clear tailpipes if using a car outdoors, and do not reenter until cleared. Brief ventilation is helpful, but professional assessment is key before returning inside.

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