Power Outages
How to keep your fridge cold during a power outage: a no-generator ice and thermometer plan
You do not need a generator to carry a fridge through a 24- to 48-hour outage. Here is the ice, where it goes, when to check the thermometer against 40 °F (4 °C), and what to do if the number climbs.
On this page (14 sections)
- How to keep your fridge cold during a power outage: the timeline
- Before the next outage: freeze water, not a shopping list
- The first four hours, step by step
- Where to put the ice, and how much of each kind
- How often to check, and the log to keep
- If the temperature climbs above 40 °F
- How to keep food cold without a fridge at all
- What this costs, and the honest answer about gear
- A 40-hour outage, worked through
- Troubleshooting
- When to get help
- Frequently asked questions
- Keep going
- Sources
You don't own a generator, the power just went out, and you're watching the fridge temperature climb with no idea whether a block of ice from the gas station will actually hold it below 40 °F (4 °C). This page is the no-generator version of how to keep your fridge cold during a power outage: ice, closed doors and one appliance thermometer, on a timeline you can follow by the clock.
The published numbers come from the FDA. An unopened refrigerator keeps food cold for about 4 hours. A full freezer holds its temperature for about 48 hours; a half-full one, about 24. The safe lines are 40 °F or below in the refrigerator and 0 °F (-18 °C) or below in the freezer, read on an appliance thermometer kept in each unit. Ice buys you time; the thermometer tells you whether it is working.
One honest limit: the FDA recommends buying block or dry ice to keep the refrigerator as cold as possible during a long outage, but it does not give a bag count for a fridge. Your thermometer reading is the number that decides, which is why it is the one small thing worth having before the next storm.
Key takeaways
- An unopened fridge keeps food cold about 4 hours; a full freezer about 48 hours; a half-full freezer about 24 (FDA).
- 40 °F (4 °C) is the decision line for the fridge, 0 °F (-18 °C) for the freezer, read on appliance thermometers (FDA).
- Freeze containers of water now: they keep food cold, and the meltwater is drinking water if your supply is affected (FDA).
- Have a cooler ready before the 4-hour mark, with ice or frozen gel packs (FDA).
- Fifty pounds of dry ice should keep a fully stocked 18-cubic-foot freezer cold for about two days (FDA).
- Once frozen food warms past 40 °F, bacteria that were already present can multiply (NCHFP). When in doubt, throw it out (CDC).
If the power just went out, do this first
- Note the time. Every step below is measured from it.
- Shut both doors and stop opening them to look. The FDA's advice is to keep them closed as much as possible.
- Read the fridge and freezer thermometers and write the numbers down.
- If the outage could pass 4 hours, get the cooler and the ice ready now (FDA).
Things this guide mentions
Amazon searches, not product picks: we have not tested what they show. Check the specs and the return policy on each listing before you buy.
How to keep your fridge cold during a power outage: the timeline
The FDA's 4-hour figure is the hinge. Before it, you are protecting cold air. After it, you are adding cold and checking temperatures. The table turns that into a schedule.
| When | Do this | What you're watching |
|---|---|---|
| Hour 0 | Note the time. Shut both doors. Read and log both thermometers. | Your starting temperatures. |
| 0 to 4 hours | Leave the doors shut. Eat from the pantry. Get the cooler, ice and gel packs ready. | The FDA's 4-hour window for an unopened fridge. |
| Around 4 hours | Move perishables into the cooler. Add ice to the fridge and freezer compartments. | The fridge thermometer against 40 °F. |
| About 12 hours | Log both thermometers again. Add ice. Drain meltwater from the cooler. | Whether the numbers are holding or trending up. |
| About 24 hours | Log again. The FDA's estimate for a half-full freezer runs out around here. | Ice crystals in frozen packages; 40 °F or below. |
| About 48 hours | Log again. Sort frozen food item by item before you refreeze anything. | The FDA's estimate for a full freezer ends about here. |
| Power back | Read both thermometers before restocking. Sort food with a keep-or-toss chart. | Any item that climbed above 40 °F. |
Two things decide how much slack you get inside those windows: how cold the fridge was when the power failed, and how often the door opens. A fridge that was already at 35 °F starts with a cushion. Every look inside spends it.
Before the next outage: freeze water, not a shopping list
Most of this plan is cheaper to set up in advance, and much of it costs nothing. The FDA's pre-storm list is short:
- Put an appliance thermometer in the fridge and the freezer. Set the fridge to 40 °F or below and the freezer to 0 °F or below. During an outage those two dials are how you decide what is safe (FDA).
- Freeze containers of water. The FDA recommends it for keeping food cold in the freezer, the refrigerator or a cooler, and the melting ice becomes drinking water if your supply is affected. The emergency water storage guide covers containers that freeze well.
- Freeze gel packs and make ice cubes ahead, and store them in the freezer for the fridge or a cooler (FDA).
- Freeze what you won't use right away — leftovers, milk, fresh meat and poultry — so it stays at a safe temperature longer, and group food together in the freezer (FDA).
- Keep a cooler on hand for refrigerated food if the power will be out more than 4 hours (FDA).
- Find out where block ice and dry ice are sold near you before you need them (FDA).
The budget angle: water bottles you already own do most of the work and cost nothing to replace. A freezer with its gaps filled with water containers is a freezer with extra cold stored in it.
The first four hours, step by step
Note the time and close the doors
Write the time the power failed on a sticky note on the fridge, then stop opening the doors; the FDA's guidance is to keep them closed as much as possible to hold the cold in.
Done when: the start time is written down and both doors are shut.
Read both thermometers and log them
Appliance thermometers are what tell you whether food is safe during an outage (FDA). A fridge at 40 °F or below, or a freezer at 0 °F or below, means you are still inside the safe zone.
Done when: you have two numbers and a time written next to them.
Have the cooler cold before the 4-hour mark
The FDA advises having coolers on hand if the power will be out more than 4 hours. Pack gel packs or frozen water bottles in it now, so it is cold before the food goes in.
Done when: the cooler is closed and cold inside.
Move the perishables, then add ice
At or near the 4-hour mark, move the perishables into the cooler: the FDA singles out leftovers, milk and fresh meat and poultry as the items to keep cold. Put frozen bottles or block ice on a tray near the top of the fridge so meltwater doesn't soak the shelves, fill the freezer gaps, and shut both doors until your next check. Do not sort food by look or smell at this stage; the keep-or-toss chart for fridge food without power does that job, item by item, when you are ready to decide.
Done when: the perishables are in the cooler, ice is in both units, and the doors are closed.
Where to put the ice, and how much of each kind
Each kind of ice behaves differently, and only one comes with a published quantity.
| Ice | Where it goes | What the sources say |
|---|---|---|
| Frozen water bottles and containers | Freezer gaps first, then the fridge's upper shelf, then the cooler | The FDA recommends freezing containers of water to keep food cold in the freezer, fridge or cooler; the meltwater is also drinking water |
| Ice cubes and frozen gel packs | Around food in the cooler; spares in the freezer | The FDA suggests making ice cubes and freezing gel packs ahead for exactly this |
| Block ice | On a tray or in a bin high in the fridge, so meltwater doesn't soak food | The FDA recommends block or dry ice to keep the refrigerator as cold as possible during a long outage; no quantity is given |
| Dry ice | In the freezer, not touching food directly | Fifty pounds should keep a fully stocked 18-cubic-foot freezer cold for about two days (FDA) |
Dry ice is far colder than water ice and can burn skin, so handle it with insulated gloves and keep the room ventilated. For block ice, there is no official number to work from: add it, shut the door, and let the thermometer tell you at the next check whether you added enough.
Watch for: generators and carbon monoxide
If you borrow a generator for the fridge, the American Red Cross says never run it inside a home, garage, basement, crawlspace or any partly enclosed area; opening doors and windows does not prevent carbon monoxide buildup. Ready.gov says to run it outdoors only, well away from doors, windows and vents, and to install battery-powered carbon monoxide alarms. Never plug a generator into a wall outlet: the Red Cross says this "backfeeding" puts utility workers and your household at risk, and a permanent connection needs a transfer switch installed by a licensed electrician. If a carbon monoxide alarm sounds, get everyone outside and call 911.
How often to check, and the log to keep
Every door opening costs cold air, so check on a schedule instead of peeking: at the start, at the 4-hour mark, and each time you add ice or move food. After that, check at roughly the same times each day and write the numbers down. A written log shows whether the temperature is holding or climbing, and gives you a record to sort food by when the power returns.
| Time | Fridge °F | Freezer °F | Ice added | Action |
|---|---|---|---|---|
No appliance thermometer yet? A food thermometer used on individual items still tells you what you need to know, but it means opening the door more often. The FDA recommends appliance thermometers in both units so you don't have to guess.
If the temperature climbs above 40 °F
This is the moment the plan exists for. Work through it in order instead of judging by look or smell.
Shut the door and add cold
Add ice, a frozen water bottle or a gel pack, then close the door. Don't stand with it open while you think.
Done when: new ice is in and the door is shut.
Move the perishables to the cooler
Milk, meat, poultry, fish, leftovers and other perishables go into the cooler with ice, packed full and kept in the coolest spot you have.
Done when: the cooler is packed, closed and out of sunlight.
Re-read the thermometer after the ice has had time to work
Give the cold a chance to move through the box, then read and log both units. You want the fridge back at 40 °F or below.
Done when: the new numbers are written down.
Decide item by item, and never taste to test
The NCHFP explains the risk plainly: as soon as frozen food begins to defrost and warms above 40 °F, bacteria that were present before freezing can start to multiply. The FDA says you can't rely on appearance or odor, so the reading and the clock decide. Use the linked keep-or-toss chart to sort each item, and throw out anything you can't clear (CDC).
Done when: every questionable item is in a keep pile or the trash.
How to keep food cold without a fridge at all
If the fridge is out of service, or you have emptied it, the cooler becomes the fridge.
- Pack the cooler full. Fill gaps with frozen bottles or crumpled newspaper; a full cooler holds cold far better than a half-empty one.
- Put it in the coolest place you have — a shaded room, a basement, out of sunlight.
- Drain meltwater and top up the ice when you check, and open the lid as little as possible.
- Eat from the pantry first. Shelf-stable meals stretch the cooler food; the emergency food supply list covers meals that need no refrigeration.
- Cook what is thawing. If frozen meat has thawed but stayed cold, cooking it uses it up; the refreezing guide covers when refreezing is safe instead.
If you thaw anything on purpose, the NCHFP's rules are strict: never thaw food at room temperature or in warm water, because the outer layer sits in the 40 to 140 °F danger zone where bacteria multiply quickly. Thaw in the refrigerator at 40 °F or less, in cold running water under 70 °F, or in the microwave if you are cooking it immediately. And don't move food outdoors to keep it cold in winter; sun, animals and temperatures that swing above freezing make it unreliable.
What this costs, and the honest answer about gear
This plan runs on things a household mostly already owns: water bottles in the freezer, a cooler, a few gel packs. The one purchase that changes the whole outage is an appliance thermometer for each unit, because it turns "I think it's still cold" into a number you can act on.
This page will not hand you a cart. Guides here explain what to look for and link to a search, not to a specific "best" model, and no product has been tested by anyone: there is no test kitchen or lab behind this site. If you want a thermometer or reusable ice packs, these are searches: appliance thermometers (Amazon, affiliate link) opens in a new tab and reusable ice packs (Amazon, affiliate link) opens in a new tab.
The same standard applies where a mistake can actually hurt someone. The canning guides use the tested methods and processing times published by the National Center for Home Food Preservation and the USDA Complete Guide to Home Canning, including altitude adjustments for pressure canning, and untested shortcuts are named only to warn against them. No one here is an emergency manager or a food scientist, and the About page says so. What you can check is the sources: the numbers on this page come from the FDA and the NCHFP, and the generator safety note from Ready.gov and the American Red Cross.
A 40-hour outage, worked through
A family of four loses power at 7 p.m. during an ice storm. The freezer is about two-thirds full of food plus four frozen water bottles; the fridge reads 38 °F and the freezer 2 °F, and both are logged. Nobody opens either door that evening; dinner comes from the pantry. At 11 p.m., the 4-hour mark, the milk, chicken and leftovers go into a cooler with two gel packs and a frozen bottle, and two more frozen bottles go on the top shelf of the fridge. At 7 a.m., 12 hours in, the fridge reads 41 °F and the freezer 12 °F; more ice goes in and both numbers are logged. By the evening check, about 24 hours in, the fridge is back to 39 °F. Power returns mid-morning, about 40 hours in. The cooler food is cooked or eaten that day; most freezer packages still have ice crystals and are refrozen; one package of fish that fully thawed and read 45 °F is thrown out; everything left in the fridge is checked against the keep-or-toss chart before it goes back into service.
Troubleshooting
- If there is no thermometer in the fridge
- Use a food thermometer on individual items and open the door as little as possible, then put appliance thermometers in both units as soon as you can (FDA).
- If the fridge is already above 40 °F at the first check
- Skip to the cooler step: pack the perishables with ice, add ice to the fridge, and log the new readings.
- If you can't buy block ice anywhere
- Use frozen water bottles and gel packs from your own freezer, grouped high in the fridge. Freezing containers of water is the FDA's own pre-outage advice.
- If the freezer door was left open for hours
- Check packages for ice crystals and read the temperature before refreezing anything, and treat fully thawed, warm food as suspect (CDC).
- If you're tempted to put food on the porch in winter
- Don't count on it: sun, animals and temperatures that rise above freezing make outdoor storage unpredictable.
When to get help
Call for help if
- Anyone gets sick after eating food you were unsure about: contact a health care provider.
- A carbon monoxide alarm sounds, or anyone feels dizzy, headachy or nauseous near a generator, grill or heater: get everyone outside, then call 911.
- Your outage is likely to run past two days and you have infants, older adults or medical equipment in the home: call your local emergency management office about warming or charging centers.
- You are unsure whether a home-canned or frozen item is safe and no temperature record exists: ask before you eat it.
Who to ask. In an emergency, call 911. If a carbon monoxide alarm sounds or anyone feels dizzy, sick or confused, get everyone outside into fresh air first, then call 911. Report outages and downed power lines to your utility. For local hazards, shelters and alerts, contact your city or county emergency management office (start at Ready.gov).
Frequently asked questions
How do I keep my fridge cold without power?
Keep the doors shut and start checking temperatures. The FDA says an unopened fridge holds food cold about 4 hours, so have a cooler ready with ice or frozen gel packs before that mark. Add frozen water bottles or block ice high in the fridge, log the thermometer at each check, and move the perishables to the cooler if the reading climbs toward 40 °F (4 °C).
How much dry ice do I need to keep a fridge cold?
No published amount exists for a refrigerator. The FDA's figure is for a freezer: 50 pounds of dry ice should keep a fully stocked 18-cubic-foot freezer cold for about two days. For a fridge, buy block ice if you can, add it high in the box, and let the thermometer tell you whether it is enough. Dry ice is extremely cold, so use insulated gloves.
Will a block of ice from the gas station keep my fridge below 40 °F?
It depends on the fridge, how full it is, how warm the room is and how often the door opens, which is why no source publishes a bag count. The FDA recommends block or dry ice for a prolonged outage, and an appliance thermometer is how you confirm it worked. Check at the 4-hour mark and again when you add ice.
How long will food stay cold in an unopened refrigerator?
About 4 hours for the refrigerator, according to the FDA. A full freezer holds its temperature about 48 hours and a half-full freezer about 24 hours with the door closed. After those windows, temperature decides: food at 40 °F or below is still in the safe zone, and food that sat warmer is a when-in-doubt-throw-it-out call (CDC).
How do I keep stuff cold without a fridge or cooler?
Perishables are hard to keep safe without an insulated box and a cold source. The FDA advises having coolers on hand before an outage and freezing containers of water for ice. Without either, plan on shelf-stable food from the pantry until the power returns, and don't count on a cold windowsill or porch.
Ready to compare?
The same searches, in one place. Use the checklist in this guide when you compare listings, and buy only what fills a gap in what you already have.
Sources
- Food and Water Safety During Power Outages and Floods, U.S. Food and Drug Administration (accessed October 30, 2026).
- Thawing and Preparing Foods for Serving, National Center for Home Food Preservation (accessed October 30, 2026).
- Power Outages, Ready.gov, FEMA (accessed October 30, 2026).
- Generator Safety, American Red Cross (accessed October 30, 2026).
- Keep Food Safe After a Disaster or Emergency, Centers for Disease Control and Prevention (accessed October 30, 2026).
The whole outage, in order
Food safety first, then light, water, warmth and generator safety: the full before, during and after plan for a power outage.