Emergencies & Disasters
How to Keep Food Cold During a Long Power Outage
General information only, not professional advice. In an emergency, call 911 and follow local officials. How we use sources
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In this guide
The CDC says: “A full freezer will keep food safe for 48 hours (24 hours if half-full) without power if you don’t open the door.” “Your refrigerator will keep food safe for up to 4 hours without power if you don’t open the door.” (CDC) For longer outages, move food to iced coolers before then. When in doubt, throw it out.
A long outage is mostly a timing problem, plus one firm rule about what to throw out. This page sticks to what the federal agencies say, quotes their words, and says plainly where they give no number. Follow the instructions from your local emergency officials over anything here, and call 911 if someone is sick or in danger.
How long will food stay cold without power?
Ready.gov, the federal preparedness site, gives the same windows and adds what to do next:
Keep freezers and refrigerators closed. The refrigerator will keep food cold for about four hours. A full freezer will keep the temperature for about 48 hours. Use coolers with ice if necessary. Monitor temperatures with a thermometer. Throw out food if the temperature is 40 degrees or higher.
Source: Ready.gov, Power Outages, accessed November 2026.
FoodSafety.gov, run by the federal food safety agencies, adds what to throw out and when:
As the USDA notes in Keeping Food Safe During an Emergency, your refrigerator will keep food safe for up to 4 hours during a power outage. Keep the door closed as much as possible. Discard refrigerated perishable food such as meat, poultry, fish, eggs, and leftovers after 4 hours without power.
A full freezer will hold a safe temperature for approximately 48 hours (24 hours if it is half full and the door remains closed). Food may be safely refrozen if it still contains ice crystals or is at 40°F (4°C) or below, however, its quality may suffer. Never taste food to determine its safety.
Source: FoodSafety.gov, Food Safety During Power Outage, accessed November 2026.
Two things follow from the CDC numbers. A full freezer holds for twice as long as a half-full one, so a packed freezer is a better bet than a half-empty one. And the fridge is the short clock: FoodSafety.gov says to discard refrigerated perishables after 4 hours without power, so decide early about coolers.
What should you do before the power goes out?
Most of the work is done in advance, and none of it is complicated.
- Get a thermometer you can read without opening the door. Ready.gov says to monitor temperatures with a thermometer, and you cannot do that without one. An appliance thermometer for the fridge and freezer.
- Know where your cooler and ice are. Ready.gov says to use coolers with ice if necessary. A cooler and a few reusable ice packs in the freezer are ready when you need them.
- Keep the freezer full. The CDC’s 48 hours is for a full freezer and 24 for a half-full one. Our own habit, not an agency’s advice, is to fill spare space with bottles of water so they freeze solid and can go into a cooler later.
If a winter storm is the reason you are reading this, the winter storm prep timeline shows when to fit these steps in. For the rest of the first hour, see what to do during a power outage at night.
Which ways of keeping food cold compare best?
The agencies agree on the basics: keep the doors shut, use coolers with ice, and watch the thermometer. They do not give hold times for coolers, because the time depends on the cooler, the ice and the room. We did not find a federal number for any of the methods below, so the last column says so instead of guessing.
| Method | What it takes | What the federal pages say | Hold time |
|---|---|---|---|
| Keep fridge and freezer doors shut | Nothing | CDC and Ready.gov: keep the doors closed | Fridge about 4 hours, full freezer about 48 hours, half-full freezer 24 hours (CDC) |
| Cooler with ice | A cooler and ice | Ready.gov: use coolers with ice if necessary | No federal number. Check the thermometer |
| Frozen water bottles or reusable ice packs | Freezer space in advance | Not named on the pages we read. Our own habit | No federal number. Check the thermometer |
| Block ice (a large frozen block) | Ice from a supplier, or a freezer-safe container you fill and freeze | Not named on the pages we read. Our own habit | No federal number. Check the thermometer |
| Appliance thermometer | Nothing beyond the thermometer | Ready.gov: monitor temperatures with a thermometer | Not applicable. It tells you when to throw food out |
Whatever you use, the line does not move: Ready.gov says to throw out food when the temperature is 40 degrees or higher. A cooler that “feels cold” is not a measurement.
What about dry ice?
This page leaves dry ice out. We could not quote an official ventilation warning for it from a federal page we were able to read, and we do not give safety instructions we cannot trace to an authority. If you buy dry ice anyway, follow the supplier’s handling instructions and ask your local officials.
How do you move food to coolers?
Do it once, quickly, and before the fridge’s four hours are up, since FoodSafety.gov says to discard refrigerated perishables after 4 hours without power. Keep the fridge door shut otherwise. Pack the coolers with ice, put a thermometer in each, and keep the lids closed. That is our practical suggestion, and it fits the Ready.gov steps above (coolers with ice, monitor with a thermometer). If a neighbor has power and a working freezer, ask before you move anything, and keep the same 40 degree rule.
When should you throw food out?
Ready.gov is direct about it:
When in doubt, throw it out! Throw away any food that has been exposed to temperatures 40 degrees or higher for two hours or more, or that has an unusual odor, color or texture.
Source: Ready.gov, Power Outages, accessed November 2026.
So the checks are time, temperature and the way the food looks and smells, and any one of them is enough to toss it. If you are not sure how long something sat warm, treat that as a reason to throw it out. Canned goods are a different question; see how long canned food actually lasts. For a food-by-food view of the first four hours, see how long food lasts in the fridge without power.
Frequently asked questions
How long will a refrigerator keep food safe without power?
The CDC says: “Your refrigerator will keep food safe for up to 4 hours without power if you don’t open the door.” (CDC) If the outage will run longer, move perishables into a cooler with ice before the four hours are up. FoodSafety.gov says to discard refrigerated perishable food after 4 hours without power.
How long does a full freezer stay cold?
The CDC says: “A full freezer will keep food safe for 48 hours (24 hours if half-full) without power if you don’t open the door.” (CDC) Keep the door shut, because every opening shortens that window.
How long will a cooler with ice keep food cold?
No federal page we read gives a number. Ready.gov says to use coolers with ice if necessary, monitor temperatures with a thermometer, and throw out food at 40 degrees or higher. Let the thermometer decide, not the clock.
What about refrigerated medicine?
Ready.gov says: “If the power is out for more than a day, discard any medication that should be refrigerated, unless the drug’s label says otherwise. Consult your doctor or pharmacist immediately for a new supply.” (Ready.gov) Ask your doctor or pharmacist before an outage which of your medicines this covers.
Can I tell if food is safe by looking at it or smelling it?
Not on its own. Ready.gov lists an unusual odor, color or texture as a reason to throw food away, but it also says to throw out anything held at 40 degrees or higher for two hours or more, however it looks. When in doubt, throw it out.
Final thoughts
Tonight, put a thermometer in the fridge and freezer and find your cooler. Then write down where both live, along with your utility numbers, on the binder checklist so anyone in the house can act fast. If the outage drags on, follow your local officials, and do not gamble with food you are unsure about.
