Food Safety During a Power Outage
USDA and FoodSafety.gov say a closed refrigerator holds perishable food safely about 4 hours without power. A full freezer holds about 48 hours; a half-full freezer about 24 hours. After that, or if perishable food has been above 40°F for more than 2 hours (1 hour above 90°F), throw it out. Never taste food to decide whether it is safe.
A long blackout turns the refrigerator into a countdown clock. 90 Days Without Power by Robert Smythe uses USDA / FoodSafety.gov / Ready.gov times rather than kitchen folklore. Appliance thermometers in the fridge and freezer tell you what actually happened after the lights went out.
The official times, with the door closed
Fridge: about 4 hours. Full freezer: about 48 hours. Half-full freezer: about 24 hours. Those figures assume you are not standing there deciding what to eat.
Keep doors closed as much as possible. A packed cooler with ice can buy more time after those windows. Ready.gov repeats the same fridge and freezer figures and tells you to monitor temperatures with a thermometer.
Forty degrees Fahrenheit (4°C) is the keep-or-toss line for perishable food. FoodSafety.gov: a perishable food that has been above 40°F for more than 2 hours, or 1 hour above 90°F, should be thrown out.
Throw out meat, poultry, fish, eggs, and leftovers from a refrigerator that has been without power for 4 hours or more. Throw out perishable freezer food that has thawed. When in doubt, throw it out.
What to keep on the shelf instead
Shelf-stable meals that do not need a fridge or a long cook will matter more than a clever recipe.
A manual can opener belongs in every kit that includes canned food (Ready.gov). Eat moist canned foods if you are stretching water. Do not cook indoors with charcoal or an unvented camp stove just to save a thawing roast; carbon monoxide is the worse emergency. See generator and CO safety.
Plan a keep-or-toss card before the next storm so you are not negotiating with a warm gallon of milk at midnight. The book's food chapter includes diagrams for cooler packing and the official timeline.
How to use thermometers and coolers so you are not guessing
An appliance thermometer in the refrigerator and another in the freezer tell you whether food stayed at 40°F or below. A cooler with ice is a second refrigerator after the official time windows run out.
Buy the thermometers before the outage. FoodSafety.gov and USDA tell you to keep the refrigerator at or below 40°F and the freezer at 0°F in ordinary life; those same instruments become decision tools when the power fails. If you arrive home after hours away and the fridge thermometer reads 45°F, you do not need to debate the four-hour rule. You need the keep-or-toss list.
A full freezer stays cold longer than a half-full one because frozen mass is thermal storage. That is why the official figures differ: about 48 hours if full, about 24 hours if half full, door closed. Grouping food together helps. Filling empty space with containers of water that you freeze in ordinary times is a legitimate household tactic; those bottles also become drinking water if they were frozen clean.
When you move food to a cooler, keep raw meat separate and sealed so juices cannot contaminate ready-to-eat food. Use ice or frozen gel packs. A cooler in the shade lasts longer than a cooler in a hot car. In desert heat, even a good cooler is a short bridge. Do not refreeze meat that has thawed and warmed above 40°F.
Baby formula, leftover rice, cut fruit, dairy, and deli meats are not items to “see if they smell fine.” Official guidance is not to taste food to decide. When in doubt, throw it out. The cost of replacing groceries is lower than the cost of foodborne illness in a house that may already lack running water and easy laundry.
Medicines that need refrigeration are a clinician question, not a leftover-chicken question. CDC says that if power is out for a day or more, throw away medication that should be refrigerated unless the label says otherwise, and consult a clinician or pharmacist about replacement. FDA publishes product-specific notes for insulin in emergencies. Follow the label and the pharmacist, not a general blog paragraph.
Cooking without putting carbon monoxide into the house
Eat no-cook food first. If you cook, do it outdoors with equipment meant for outdoor use, and never bring a grill or camp stove inside to save thawing meat.
Ready.gov lists a manual can opener in a basic kit because canned food is only useful if you can open it. Favor foods your household already eats so rotation is ordinary life, not a separate “apocalypse pantry” you will not touch and will not know how to cook.
A propane camp stove and a charcoal grill are outdoor tools. The carbon monoxide rules on the generator page apply. Do not cook in a garage with the door cracked. Do not cook in a tent. After floods or boil-water notices, use safe water for washing produce and for anything that touches food. See boil-water advisories.
If you must discard a lot of food, document what you threw out if your insurer or a disaster program later asks for a list; that is paperwork, not a reason to keep unsafe food “for the claim.” Take photographs of thermometer readings if you can.
Chapter 5 of 90 Days Without Power includes the official timeline as a diagram and a keep-or-toss worksheet. Pair that chapter with the water guides, because dishwashing and handwashing collapse if you treated every last gallon as drinking water and left none for sanitation.
A simple keep-or-toss walk-through
Throw out perishable refrigerated food after about 4 hours without power, and throw out perishable food that has been above 40°F for more than 2 hours (1 hour if the air is above 90°F). Frozen food that still has ice crystals and has stayed at 40°F or below can usually be refrozen or cooked, following USDA tables.
USDA and FoodSafety.gov publish detailed keep-or-toss tables for categories such as meat, poultry, seafood, dairy, leftovers, and condiments. Hard cheeses, butter, and many condiments often last longer than milk or leftover stew; the tables, not memory, should decide. Print or save those official tables with your kit so you are not using a search engine on a dying phone.
If a freezer stayed closed and food still has ice crystals, USDA says it is generally safe to refreeze, though quality may drop. If it thawed and warmed above 40°F for more than 2 hours, throw it out. Do not rely on odor. Some harmful bacteria do not change the way food smells.
In very hot indoor air the one-hour rule for perishable food above 90°F matters. An un-air-conditioned kitchen in an Arizona outage can cross that line quickly. That is another reason the desert editions of the book treat heat and food as overlapping chapters rather than separate hobbies.
Questions people ask
How long is refrigerator food safe without power?
USDA and FoodSafety.gov say about 4 hours if the door stays closed. After that, follow the 40°F keep-or-toss rule.
Can I tell if food is safe by tasting it?
No. Official guidance is never to taste food to decide. When in doubt, throw it out.