Power Outages
Temperature danger zone in food safety: one reading, one chart
One thermometer reading decides the whole fridge: below 40 °F (4.4 °C) the food is as safe as it was, and above it the clock starts. Here is what each of four possible readings means for milk, eggs, meat, leftovers and condiments.
The power was out for 36 hours, and the chicken and the milk in the fridge became the whole question. You couldn't tell whether they were still safe, you couldn't risk being wrong, and you threw out $120 of food to end the argument.
The temperature danger zone in food safety is the band of temperatures where that decision actually gets made: 40 °F to 140 °F (4.4 °C to 60 °C). The National Center for Home Food Preservation calls it the “Danger Zone” and says plainly that bacteria multiply rapidly inside it. Below 40 °F, a perishable food is as safe as it was when you put it away. What follows is one chart, four possible thermometer readings, and a keep-or-toss answer for milk, eggs, meat, leftovers and condiments — a decision you can make in a minute instead of guessing.
What this page is, and what it is not
If your guard is up about preparedness sites, that is reasonable. The plain version: no product picks, no prices, no “must-have” gear. The only shopping links here are Amazon search links, labeled as affiliate links, for ordinary items like a thermometer, and the method works without buying any of them. Every number below is tied to a source you can open in the Sources section. This site has no staff of experts and no food-safety professional reviews these guides; pages are written with AI-assisted drafting and checked against those sources, as the how we write page explains. Canning guidance here follows USDA and NCHFP tested methods only, never a blog shortcut.
Key takeaways
- 40 °F to 140 °F (4.4 °C to 60 °C) is the danger zone, where bacteria multiply rapidly (NCHFP).
- Food is safe indefinitely while it stays frozen; the clock starts when it thaws and warms past 40 °F (NCHFP).
- An unopened fridge holds about 4 hours. A full freezer holds about 48 hours, a half-full one about 24 (FDA).
- After the power returns, a freezer thermometer reading 40 °F or below means the food is safe and can be refrozen (FDA).
- The FDA's discard list for the fridge names meat, poultry, seafood, milk, eggs and leftovers held above 40 °F for 4 hours or more.
- One narrow exception: perishable food measured at 45 °F or below should be safe, but cook it and eat it right away (FDA).
- You cannot rely on how food looks or smells. A thermometer, or ice crystals still in the package, is the only real evidence (FDA).
Things this guide mentions
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What is the temperature danger zone for food safety?
It is 40 °F to 140 °F (4.4 °C to 60 °C). Outside that band, food is either too cold for bacteria to grow quickly or too hot for them to survive.
Two rules follow, and they are most of the method. The refrigerator's job is to hold food below 40 °F, which is why the NCHFP says to thaw food in a refrigerator set at 40 °F or less, never on the counter and never in warm water. And when the power goes out, the question is not how long the lights were off. It is how warm the food got, and how long it stayed that way.
The FDA's outage advice is built on exactly that: refrigerated perishable food that has been above 40 °F for 4 hours or more should be discarded. Notice what the sentence measures — the food, not the outage. Two fridges in the same neighborhood can end the same 36 hours at 38 °F and at 52 °F, one full and shut, the other half empty and opened every hour to check.
The four-reading chart: one number, four answers
Read the thermometer before you touch anything. That number sorts every perishable in the fridge into one of four situations, and each has its own answer. The chart groups the FDA's outage rules into four readings; the grouping and the column headings are this page's arrangement, not an FDA table. The “never checked” column falls back on the FDA's 4-hour clock and, where that cannot be confirmed, on the rule FoodSafety.gov states as “when in doubt, throw it out.”
| Food | 40 °F (4.4 °C) or below | 41–50 °F (5–10 °C) | Above 50 °F (10 °C) | Never checked |
|---|---|---|---|---|
| Milk, cream, yogurt | Keep | At 45 °F or below and confirmed under 4 hours above 40 °F: use it now, do not put it back. At 46–50 °F, or 4 hours or more: discard | Discard | Under 4 hours with the door shut: use it first. Otherwise discard |
| Eggs in the shell | Keep | Same as milk | Discard | Same as milk |
| Raw meat, poultry, fish | Keep | At 45 °F or below and under 4 hours: cook it thoroughly right now. Otherwise discard | Discard | Under 4 hours with the door shut: cook it thoroughly right now. Otherwise discard |
| Cooked leftovers (soups, stews, rice, pasta, casseroles) | Keep | At 45 °F or below and under 4 hours: eat it now, do not put it back. Otherwise discard | Discard | Under 4 hours: eat it now. Otherwise discard |
| Butter, hard cheese, condiments, jam, pickles | Keep | Not on the FDA's perishable discard list — check these item by item | Same: item by item | Item by item, against the source chart |
| Bulging, leaking or damaged package | Discard | Discard | Discard | Discard |
The middle column needs one honest note. The FDA gives a general rule — discard perishables held above 40 °F for 4 hours or more — and also a narrow exception: perishable food measured with a food thermometer at 45 °F or below should be safe, but should be cooked and consumed as soon as possible. Those two sentences point slightly different ways. Treat the exception as exactly that: a measured reading at or below 45 °F, with the time above 40 °F known to be under 4 hours, and the food eaten now rather than saved. If you can confirm only one of the two, use the strict rule. The cost of one package of chicken is smaller than the cost of being wrong.
The condiment row is where most of the wasted money hides. The FDA's discard list for refrigerated perishables names meat, poultry, seafood, milk, eggs and leftovers. Mustard, jam, butter and hard cheese are not on it, and the item-by-item guidance lives on FoodSafety.gov's outage chart — so check each jar against that chart rather than clearing the door shelf out of caution, or keeping something you cannot vouch for.
Food safety fridge temperature: the clocks you are working against
Every number below assumes the door stays shut. Each opening lets cold air out and warm air in, so a fridge checked every hour is not really on this schedule.
| Where the food is | Roughly how long | What it means |
|---|---|---|
| Refrigerator, door kept shut | About 4 hours | Perishables stay below 40 °F for roughly that long; after that the clock above 40 °F starts |
| Full freezer, door kept shut | About 48 hours | Still-frozen food is safe indefinitely; once a package thaws, it gets the fridge rule |
| Half-full freezer, door kept shut | About 24 hours | Same check, sooner; a fuller freezer is easier to defend |
| Perishable food left out at room temperature | 2 hours — or 1 hour if the room is above 90 °F (32 °C) | Discard |
The FDA also gives you a head start worth taking. If the power will be out more than 4 hours, have coolers on hand and move refrigerated food into them; the cooler packing guide covers the layering order and the ice plan. Freeze water bottles, ice cubes and gel packs ahead of time, and group packages together in the freezer so they help keep each other cold. Know where block or dry ice is sold near you, too: the FDA notes that 50 pounds of dry ice should keep an 18-cubic-foot, fully stocked freezer cold for about two days.
When the power returns, the freezer check is separate from the fridge check. A freezer thermometer reading 40 °F or below means the food is safe and may be refrozen. Without one, check each package: food that still contains ice crystals, or reads 40 °F or below, is safe to refreeze or cook. Anything that fully thawed gets the fridge rules above. The freezer food safety guide walks through that part item by item.
Food safety temperature: how to take the reading, in order
Five steps, about ten minutes of attention spread across an outage. The order matters because you read before you unpack, so you get the food's real temperature and not the room's.
Keep a thermometer in the fridge and one in the freezer
An ordinary appliance thermometer is enough, and it has to live in there all the time — not be found in a drawer after the power is back. appliance thermometers for the fridge and freezer (Amazon, affiliate link) opens in a new tab.
Done when: both appliances have a thermometer you can read without hunting for it.
Shut the doors and write down the start time
The 4-hour and 48-hour figures assume closed doors. Write the outage start time on a sticky note on the fridge instead of opening it to think.
Done when: the time the power went out is written down.
Read before you unpack
When the power returns, open once and read the thermometer first. That reading decides everything else, so take it before warm room air changes the answer.
Done when: the number is written next to the outage time.
If there is no thermometer, check the packages
The FDA's fallback: look for ice crystals and check the food's temperature with a food thermometer. Food still containing ice crystals, or at 40 °F or below, is safe to refreeze or cook. What you cannot do is judge by appearance or odor — the FDA says so directly. digital food thermometers (Amazon, affiliate link) opens in a new tab.
Done when: every questionable package has been checked or thrown out.
Work the chart once, then stop
Go shelf by shelf against the four-reading chart, decide, and move on. Re-deciding the same container an hour later does not make it safer, and it is how a small loss turns into a big one.
Done when: the fridge holds only food you can account for.
Before the next outage: a 20-minute setup
- Put a thermometer in the fridge and one in the freezer today. It is the single item that turns the chart into an answer.
- Freeze water bottles and gel packs now, filled about two-thirds so they do not split, and keep them in the freezer (FDA).
- Group food together in the freezer so packages help keep each other cold (FDA).
- Get a cooler before you need one. The FDA's trigger is an outage expected to last more than 4 hours.
- Find out where block ice or dry ice is sold near you and note the number, so nobody is driving around in the dark looking for it (FDA).
- Write the outage start time on a sticky note and stick it on the fridge door. The clock is the other half of the decision.
Watch for: generators and carbon monoxide
If you run a generator to keep a fridge or freezer going, it stays outside. Never indoors, never in a garage, basement or crawl space, even with the door open, and keep it away from doors, windows and vents — the CDC puts that distance at 20 feet or more. Install battery-powered carbon monoxide alarms. Never plug a generator into a wall outlet, and never connect it to your home's wiring without a transfer switch installed by a licensed electrician; backfeed can kill a utility worker. If a CO alarm sounds, get everyone outside and call 911.
Troubleshooting
- If the reading is in the 41–50 °F band and it has clearly been under 4 hours
- Cook the perishables and eat them now, or discard them. The FDA's exception covers food measured at 45 °F or below; do not put it back to decide later.
- If the reading is in that band and you cannot say how long
- Use the strict rule and discard the perishables. The exception depends on a measured temperature and a known time, and you only have one of the two.
- If you do not own a thermometer
- Check packages for ice crystals and use a food thermometer on anything questionable. Appearance and odor prove nothing (FDA). Put an appliance thermometer in both appliances before the next storm.
- If the freezer was half full
- Plan on about 24 hours instead of 48 (FDA) and check packages sooner. Next time, fill the empty space with frozen water bottles.
- If the fridge door was opened every hour
- The 4-hour figure assumes closed doors (FDA). Treat your clock as shorter and trust the thermometer rather than the schedule.
- If a package thawed but still reads 40 °F or below
- The FDA says it is safe to refreeze or cook. Quality will suffer, so cooking it is the kinder choice — the refreezing thawed meat guide covers that call.
A 36-hour outage, decided at two checkpoints
A household of four loses power at 6 p.m. on a Friday in an ice storm. The refrigerator thermometer reads 38 °F, the freezer is full, and they write “6 p.m. Friday” on a sticky note. Both doors stay shut.
At 6 a.m. Saturday, hour 12, the fridge reads 41 °F. That is above 40 °F, but the time above it is confirmed under 4 hours, so the chicken, the milk and the leftovers are cooked and eaten that day rather than saved. Nothing is thrown out at this checkpoint.
By Saturday evening, hour 24, the fridge reads 49 °F and the time above 40 °F is now well past 4 hours. The remaining perishables go: eggs, yogurt, an open package of lunch meat, about $40. The butter, hard cheese, mustard and jam stay, because they are not on the FDA's perishable discard list.
The power returns at 6 a.m. Sunday, hour 36. The freezer packages still contain ice crystals, so under the FDA's fallback check they are safe to refreeze. Total loss, about $40 instead of $120, and each decision took under a minute because there was a number to read.
That is what the chart buys you: not a promise that nothing spoils, but a way to know which food is actually at risk and which is only sitting there looking suspicious.
When to get help
Call for help if
- A carbon monoxide alarm sounds, or anyone feels dizzy, sick or sleepy near a running generator: get everyone outside, then call 911.
- Anyone in the household feels unwell after eating food you were unsure about: contact a health care provider. This site does not give medical advice.
- You have a food safety question this chart does not answer, especially about a food that is not on the list: your local Cooperative Extension office can talk it through with you.
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
What is the temperature danger zone for food safety?
It is 40 °F to 140 °F (4.4 °C to 60 °C). The National Center for Home Food Preservation calls it the “Danger Zone” and says bacteria multiply rapidly inside it. Below 40 °F, perishable food holds; above it, bacteria already on the food can begin to grow. The FDA's outage advice is built around that line: perishables held above 40 °F for 4 hours or more should be discarded.
What is a safe food safety fridge temperature?
40 °F (4.4 °C) or below. The NCHFP's thawing guidance puts it directly: thaw food in the refrigerator at 40 °F or less, never at room temperature or in warm water. An appliance thermometer kept in the fridge is the only way to know yours is actually there, since the dial on the front is a setting rather than a reading.
Is 45 °F safe for food after a power outage?
The FDA gives one narrow exception: perishable food measured with a food thermometer at 45 °F or below should be safe, but should be cooked and consumed as soon as possible. That is not a green light to refreeze it or leave it for tomorrow. If you cannot confirm the temperature and how long it spent above 40 °F, use the stricter rule and discard it.
Do I have to throw out condiments and butter?
Not automatically. The FDA's discard list for refrigerated perishables names meat, poultry, seafood, milk, eggs and leftovers. Butter, hard cheese, condiments and jams are not on it, and the item-by-item guidance is on FoodSafety.gov's outage chart. Check each item there rather than clearing the door shelf by default — and use “when in doubt, throw it out” for anything you cannot account for.
Where can I find a temperature chart for food safety?
The four-reading chart on this page is the outage version, built from the FDA's power-outage guidance and the NCHFP's danger-zone definition. For a full item-by-item list, including foods that are not in the fridge, use FoodSafety.gov's power outage chart. Both are linked in the Sources section below, and both are free to open.
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Sources
- Food and Water Safety During Power Outages and Floods, U.S. Food and Drug Administration (accessed November 2, 2026).
- Thawing and Preparing Foods for Serving, National Center for Home Food Preservation (accessed November 2, 2026).
- Food Safety During Power Outage, FoodSafety.gov, U.S. Department of Agriculture (accessed November 2, 2026).
- Power Outages, Ready.gov, FEMA (accessed November 2, 2026).
- Preventing Carbon Monoxide Poisoning, Centers for Disease Control and Prevention (accessed November 2, 2026).
Ready for the next outage
Before, during and after an outage, in order: food safety, light, water, staying warm or cool, and generator safety.