How to Know your Freezer Lost Power and Thawed While You Were Away


If your home loses power while you are away, it will probably come back on after awhile.

You may be away on vacation, a trip, or an evacuation from a hurricane (for example).

Though you may have a clue that the home lost power when you see all your digital clocks flashing (the one on the microwave, the stove, etc,) you won’t know for how long.

The food in your freezer or refrigerator might have reached room temperature (maybe for a long time!). And that will most certainly risk bacterial growth and foodborne illness.

There are a few simple ways how to know if your freezer thawed.

Freezer Temperature Alarm

It’s not an alarm exactly, but it will let you know if the freezer thawed.

Take an ice cube or two and place in a sealed plastic bag or a see-through sealed container. Put it in the freezer.

Note: It is important for the bag (Ziploc) or container to be sealed so that the cube or cubes don’t evaporate.

If the freezer thawed, the ice cube (or cubes) would partially or completely melt from their original shape. The result would either be a badly misshapen cube or a melted and re-frozen puddle on the bottom.

You might also simply put the cubes in a small Rubbermaid container.



I like the following set of refrigerator / freezer digital thermometers with max/min temperature indicators. It’s a great way to know if your freezer thawed while you were away (just read the ‘max’ temperature),

Digital Freezer / Refrigerator Thermometer

Refrigerator Freezer thermometer with maximum minimum

Another method that I read about is this:

Freeze a cup of water. Place a coin on top. If the water remains frozen, the coin will stay on top of the ice. If it melts, then the coin will begin to sink into the cup.

What To Do With Your Chest Freezer When The Power Goes Out

1. Don’t open the freezer!

2. Cover the freezer (drape it) with several blankets (the more the better) which will help insulate it further. Be sure not to cover the motor vent or vents, so when the power comes back on they will not be obstructed.


The more full your freezer, the longer it will all stay frozen when the power goes out.

Food in a full freezer will stay frozen for about 48 hours without electricity.

Food in a half-full freezer may remain frozen only 24 hours.

A generator will keep it frozen, even if you run it for an hour, then off for a few, repeat…

If freezer food has partially thawed, or is still below 40 degrees F, it is safe to re-freeze.

When in doubt, throw it out.

If you are home when the power goes out, if it extends into day #2 and there’s doubt whether it will come back on in the next 24 hours or so,

– start eating your frozen food!

– consider home canning what you can (if you have a gas stovetop since the power is out)

– give some away, have a neighborhood block party?

Continue reading: Freezer Food Storage Shelf Life


  1. Freezer down time can be significantly extended by placing gallons of salt water in the freezer and having them frozen for such an emergency.

    Placing them in the bottom or in certain places… If the space is needed they can be pulled / replaced when space is sufficient to allow..

    BE sure to MARK salt water bottles as such…

    One can also store extra filtered water there… Salt water jugs will remain colder and harder longer than regular water…. giving you extra time to use the food or secure it into jars.

    When used with the blankets, added insulation measures…could be significant.

  2. Freeze a sandwich container of water. Place a penny on top of the ice. If the freezer gets warm, the ice will melt and the coin will sink.

  3. I fill fill a 2 liter bottle half way and freeze it on its side. Then I stand it upright in the freezer. If it thaws, the water will be on the bottom

  4. Just free water in a small clear container. Place coin on top. If coin remains on top, nothing thawed out.

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