Photo: viswaprem anbarasapandian / Unsplash (Unsplash License). General kitchen still life showing vegetables and a cutting board. Not a photograph of a power outage, refrigerator contents, or a food-safety inspection.

The lights are out, and the refrigerator is suddenly the most important clock in the house. Do you open the door to check the milk? Move everything to a cooler? Or wait and hope the food stays cold?

The useful answer is less about guessing how long a blackout will last and more about keeping doors shut, tracking time, and checking food temperature when power returns. U.S. government food-safety guidance provides three numbers worth remembering: four hours for an unopened refrigerator, about 48 hours for a full closed freezer, and about 24 hours for a half-full closed freezer. Those are planning estimates—not a guarantee for every appliance or every item.

First move: close the doors, then note the time

When power goes out, write down when it happened. Keep refrigerator and freezer doors closed except when absolutely necessary. Repeatedly opening the refrigerator to feel whether food is cold lets the remaining cold air escape, shortening the time you have. A thermometer left inside each appliance is more informative than touching a carton or guessing from the room temperature.

The U.S. Department of Agriculture recommends refrigerator temperatures of 40°F or below and freezer temperatures of 0°F (-18°C) or below during normal operation. If you have advance warning of a likely outage, freeze water in containers, chill gel packs, group frozen packages together, and prepare a cooler. The goal is to buy time without creating a food-safety gamble.

Refrigerator versus freezer: the decision table

Where the food is	Door stays closed	What to do next
Refrigerator	Up to about 4 hours	Keep closed. If the outage runs longer, move perishables to an iced cooler that stays at or below 40°F, if possible.
Full freezer	About 48 hours	Leave closed. When power returns, check each package for ice crystals or a measured temperature of 40°F or below.
Half-full freezer	About 24 hours	Expect less holding time than a full freezer. Check packages individually after the outage.
Any perishable food held above 40°F for more than 2 hours	Not a safe holding condition	Discard. Do not rely on smell, appearance, or tasting.

These guidelines answer different questions. The refrigerator’s four-hour estimate assumes the door stayed closed. The two-hour rule concerns how long a perishable food was above 40°F. Do not treat four hours as permission to keep meat, eggs, or leftovers warm for four hours. If you cannot establish safe temperature control after a prolonged outage, use the official discard guidance rather than a hopeful guess.

What usually has to go—and what may stay

After a refrigerator has been without power for more than four hours and its perishables were not kept safely cold by another means, U.S. guidance says to discard high-risk refrigerated foods. Examples include raw or cooked meat and poultry, seafood, eggs, milk, yogurt, soft cheeses, cooked vegetables, cut fruit, cut vegetables, and leftovers. Cooked rice and pasta are on the discard list when they have been above 40°F for more than two hours.

Not everything in the refrigerator has the same risk. The official FoodSafety.gov chart lists whole uncut fruits and vegetables, butter, many hard cheeses, bread, peanut butter, mustard, and pickles among foods that may be kept after the specified temperature exposure. That does not make visibly contaminated or flood-exposed food safe: discard anything exposed to raw meat juices or other contamination.

Example food	FoodSafety.gov chart when above 40°F for over 2 hours
Raw meat, eggs, milk, leftovers	Discard
Cut fruit, cut vegetables, packaged pre-cut greens	Discard
Cooked rice, cooked pasta, soups and casseroles	Discard
Whole uncut fruits and vegetables	Keep, if not contaminated
Butter and many hard cheeses	Keep, subject to the food-specific chart
Shredded cheese and soft cheeses	Discard

That table is a shortcut, not a complete inventory of every food in your home. Some products—such as opened mayonnaise and particular frozen vegetables—have more specific conditions in the official charts. For borderline items, check the exact food category instead of applying one rule to the whole shelf.

Can you refreeze thawed food?

Sometimes. If frozen food still contains ice crystals or a food thermometer shows it is 40°F or below, USDA guidance says many items can be refrozen or cooked, although texture and flavor may decline. A package that feels merely cool to the hand is not the same as a reliable temperature reading. If perishable frozen food has been above 40°F for more than two hours, discard it.

The food category still matters. For example, the official frozen-food chart advises discarding thawed ice cream even when it still seems cold, while breads without custard fillings may be refrozen. Meat or seafood contaminated by leaking raw juices should be discarded regardless of whether other packages seem salvageable. Don’t refreeze everything automatically because one item still has ice crystals.

A practical plan if the outage continues

1. At the start: note the time, leave appliance doors closed, and check your utility’s restoration updates without repeatedly opening the fridge.
2. Before four hours: if restoration looks unlikely, prepare a cooler with plenty of ice or frozen gel packs; transfer perishable refrigerator food only if you can keep it at 40°F or colder.
3. For the freezer: keep the door closed as long as possible. If the outage is prolonged, consider block ice, dry ice used with proper precautions, or a working freezer elsewhere.
4. When electricity returns: record temperatures, inspect packages one by one, and use the refrigerated and frozen FoodSafety.gov charts.
5. If you cannot verify safety: discard the questionable perishable food. Never taste it to test whether it is safe.

Avoid the tempting shortcut of putting perishables outdoors in cold weather. Outside temperatures can change, sun can warm the food, and animals or dirty surfaces can contaminate it. Use a cooler with ice and a thermometer instead. Handle dry ice carefully: it can cause serious cold burns, so follow its safety instructions and never touch it with bare hands.

What if the outage follows a flood?

A flood changes the decision. Food that came into contact with floodwater may be unsafe even if it was shelf-stable or still cool. USDA guidance advises discarding food exposed to floodwater unless it meets the agency’s narrow, food-container-specific salvage criteria. Don’t assume a sealed-looking carton or screw-top jar can be cleaned well enough to eat safely.

The short answer

Keep the doors shut. Use four hours for the unopened refrigerator and roughly 48 or 24 hours for a closed full or half-full freezer as planning guides. When power returns, the key questions are whether each food stayed at 40°F or below, whether it still has ice crystals, and whether it belongs to a discard category. An appliance thermometer and the government’s food-specific charts are more useful than a sniff test.

U.S. household food-safety reference, verified October 15, 2026. This is a practical explainer, not a report of a specific storm or an announcement of a new 2026 rule. No sponsored products or affiliate links.