TL;DR: When the power goes out, keep refrigerator and freezer doors closed, protect food by temperature, and run fuel-burning equipment outdoors only.

When electricity fails, a closed refrigerator keeps food cold for about four hours, a full freezer holds temperature for about 48 hours, and a half-full freezer holds for about 24 hours, according to Ready.gov and CDC guidance summarized by Ready & Resourceful and the Generator & Backup food-safety guide.

The first decision is the doors. According to Ready.gov, households should keep freezers and refrigerators closed during an outage. According to the CDC guidance described by Ready & Resourceful, refrigerated food can remain safe for up to four hours without power when doors stay closed. A full freezer can hold safe temperatures for about 48 hours, or about 24 hours if half full, under the same closed-door condition.

The second decision is temperature, not appearance. According to FoodSafety.gov guidance cited by Generator & Backup, food is safe below 40°F, and refrigerated perishables held above 40°F for more than two hours should be discarded. According to Ready.gov, households should use a thermometer and throw food out if the temperature is 40°F or higher. According to the American Red Cross, residents should measure refrigerator and freezer temperatures with a thermometer and throw out perishable food that has been warmer than 40 degrees Fahrenheit.

What happens to refrigerated food

The 4-hour refrigerator clock

A refrigerator without power warms faster than a freezer because it contains mostly air and chilled items rather than a solid mass of frozen food, as explained by Generator & Backup. With the door kept closed, the refrigerator keeps food cold for about four hours, according to Ready.gov.

According to Ready & Resourceful, those limits depend on the stated conditions and are not a guarantee for an appliance that was already too warm. An appliance opened repeatedly or an uncertain outage start introduces information that the headline number cannot resolve.

According to the American Red Cross, households should eat fresh, perishable foods first. According to Protocol Survival, households should eat perishable food first, then freezer food, then shelf-stable food.

According to FoodSafety.gov guidance cited by Generator & Backup, refrigerated perishables subject to discard after unsafe exposure include meat, poultry, fish, eggs, dairy, cut fruit, and leftovers. According to Osprey Zero’s food-safety guide, after four hours without power or another cold source, refrigerated perishables such as meat, eggs, and leftovers should be discarded.

What to do in the first hour

According to Ready & Resourceful, households should note when the interruption was discovered and whether that time is also the known start time. The note should be placed where household members can find it without needing a phone.

According to Ready & Resourceful, every member should be told to leave refrigerator and freezer doors closed. Without that instruction, each person may open the door to check whether the light has returned.

According to Protocol Survival, households should report the outage to the utility and check whether the problem affects only the home, the street, or a wider area. According to PowerProofHome, households should check whether neighbors also lost power, report the outage, keep refrigerator and freezer doors closed, unplug sensitive electronics, and use flashlights instead of candles.

According to Protocol Survival, phones should be switched to low-power mode and screen brightness turned down. According to Protocol Survival, one lamp should be left switched on so residents know when power returns.

What happens to frozen food

The 48-hour and 24-hour freezer clocks

A full freezer holds temperature for about 48 hours with the door closed, according to Ready.gov. A half-full freezer holds for about 24 hours with the door closed, according to FoodSafety.gov guidance cited by Generator & Backup and CDC guidance cited by Ready & Resourceful.

According to Generator & Backup, filling empty freezer space with sealed jugs of water and freezing them increases thermal mass. That publication states that the practice can move a half-empty freezer toward the 48-hour figure, provide frozen blocks for transfer to the refrigerator compartment, and leave drinking water when the ice melts.

According to the CDC guidance described by Ready & Resourceful, normal storage targets are 40°F or below in the refrigerator and 0°F or below in the freezer. According to Generator & Backup, placing one appliance thermometer in the refrigerator and one in the freezer allows residents to read temperatures after power returns instead of guessing.

When frozen food can be kept

According to FoodSafety.gov guidance cited by Generator & Backup, frozen food still containing ice crystals or at 40°F or below can be safely refrozen. According to Osprey Zero, food with ice crystals or at 40°F or below can generally be refrozen or cooked, subject to the item-specific chart.

According to Ready & Resourceful, the FoodSafety.gov refrigerated-food chart lists decisions for items exposed to 40°F or above for more than two hours and separates categories such as meat, dairy, fruit, sauces, grains, and vegetables. According to that publication, households should find the actual item and stated condition rather than copying an adjacent row.

According to CDC guidance described by Osprey Zero, cooking is not a rescue plan for unsafe storage. Households should make the storage decision first, then cook only food that remains safe to use.

According to CDC guidance and FoodSafety.gov charts described by Osprey Zero and Ready & Resourceful, households should never taste questionable food to check safety. According to the American Red Cross, when in doubt, throw it out.

What happens to lights, electronics, and water

Protecting appliances from restoration surges

According to Ready.gov, households should turn off or disconnect appliances and electronics. Ready.gov states that power can return with surges or spikes that damage them.

According to the American Red Cross, residents should unplug appliances and electronics to avoid damage from power surges and leave one light on to know when power is restored. According to Protocol Survival, sensitive electronics and appliances should be unplugged to protect them from surges when power returns.

According to Protocol Survival, households should wait a few minutes before plugging appliances back in, one at a time, after power returns.

Light, information, and phone power

According to the American Red Cross, residents should use flashlights or battery-operated lanterns, not candles, to help avoid fires. According to Protocol Survival, households need one flashlight or LED lantern per person plus spare batteries and should avoid candles because they are a leading cause of fires during outages.

According to Protocol Survival, each household needs one battery-powered or hand-crank NOAA Weather Radio plus spare batteries. According to that publication, households need one charged power bank per person, and a portable power station or solar charger is needed for longer outages or medical devices.

According to Protocol Survival, information during an outage should come from a NOAA Weather Radio, local AM/FM stations, and Wireless Emergency Alerts.

Water and sanitation

According to Ready.gov guidance cited by PowerProofHome, households should store at least one gallon of water per person per day for several days, with more needed in hot weather or for pets. According to Protocol Survival, households need one gallon per person per day, with a three-day minimum and a two-week goal, plus additional water in heat, for nursing mothers, and for pets.

According to Protocol Survival, households should fill bathtubs and clean containers with water while pressure is still on. According to that publication, toilets may not flush if water pressure drops. According to Protocol Survival, households should follow any boil-water advisory until the utility lifts it.

According to Protocol Survival, households should keep cash in small bills because card readers and ATMs stop working. That publication lists $100 to $200 in small bills as a three-day minimum and $300 or more as a longer goal. According to the same checklist, drivers should fill the car’s gasoline tank because station pumps need electricity.

What happens when backup heat or power is used

Generators, stoves, and grills

According to Ready.gov, generators and fuel must stay outdoors at least 20 feet from windows, doors, and attached garages. According to the same guidance, households should install carbon monoxide detectors, keep the generator dry, connect appliances with heavy-duty extension cords, and let the generator cool before refueling because fuel spilled on hot engine parts can ignite.

According to the American Red Cross, a generator, grill, camp stove, or other gasoline, propane, natural gas, or charcoal-burning device should never be used inside a home, garage, basement, or other partially enclosed area. That organization states that such equipment should be kept outside and away from doors, windows, and vents.

According to the American Red Cross, appliances should be plugged directly into the generator, and a generator should never be plugged into a wall outlet. According to Ready.gov guidance summarized by the generator-safety publications, feeding house circuits requires a transfer switch installed by a licensed electrician and a permit where local code requires one.

According to the American Red Cross, generators should be operated on a dry surface, kept dry, and not used in wet conditions or touched with wet hands. According to Ready.gov, a gas stove or oven should never be used to heat a home because that raises the risk of carbon monoxide poisoning, fire, burns, and appliance damage.

Carbon monoxide response

According to the Consumer Product Safety Commission warning described in the October 3, 2026 generator-safety guide, portable generators are one of the leading causes of post-storm carbon monoxide deaths. That warning describes carbon monoxide as a colorless, odorless gas that can kill within minutes.

According to Protocol Survival, carbon monoxide is invisible and odorless. That publication states that if anyone feels dizzy, nauseous, has a headache, or is confused while a generator or fuel-burning heater is running, everyone should move into fresh air immediately and call 911.

According to the American Red Cross, carbon monoxide kills, and anyone who starts to feel sick, dizzy, or weak should get to fresh air right away.

Who faces higher risk and when to leave

According to Ready.gov winter guidance summarized by Family Guard Plan, older adults, children, sick individuals, and pets face greater risk when winter storms cut off heat, power, and communication. According to Protocol Survival, residents should check on everyone in the house and on elderly neighbors when power fails.

According to the American Red Cross, residents should decide whether to leave if the home becomes too hot or cold or if household members use medical devices that need power. According to that organization, residents should check with loved ones and neighbors to see whether they need help.

According to the American Red Cross, residents should not drive unless necessary because traffic lights will be out and roads could be congested. According to Protocol Survival, residents should stay away from downed power lines, assume every line is live, and report it to the utility or 911.

Medications and medical devices

According to Protocol Survival, households should keep at least seven days of prescription medications, plus a written list of doses and pharmacy and doctor numbers. According to Ready.gov guidance summarized in the generator-use guide, households needing refrigerated medicine or powered medical devices should make a plan with their provider.

According to Ready.gov guidance cited by Family Guard Plan, refrigerated medication should be discarded if power is out for more than a day unless the label says otherwise, and residents should ask a pharmacist or doctor about a replacement.

Cooler use and no-cook eating

According to the American Red Cross, refrigerator and freezer doors should be kept closed as much as possible, and coolers with ice should be used if necessary. According to CDC guidance described by Ready & Resourceful, refrigerated perishables should be moved into a cooler with ice or another cold source after four hours, while maintaining 40°F or below.

According to Osprey Zero, the cooler, ice or frozen packs, thermometer, and meal plan should be prepared first so the refrigerator door does not remain open while supplies are gathered. According to that publication, raw foods should be contained so they cannot leak onto ready-to-eat food.

According to Protocol Survival, households need shelf-stable food that needs no cooking plus a manual can opener. That publication lists canned meat, beans, soups, peanut butter, crackers, oats, and dried fruit. According to Osprey Zero, households should open only what can be eaten safely when refrigeration is unavailable and read labels for storage after opening.

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