Home / Emergency food

Choose a refrigerator thermometer before the power goes out

By the Plain Prepper editors. Updated 2026-10-18.

We research products from makers' specs, manuals and safety agencies; we do not run hands-on tests. Links to Amazon may earn us a commission at no cost to you. How this works.

Quick answer

Put a thermometer in both the refrigerator and the freezer before an outage. FoodSafety.gov says the freezer should be at or below 0 degrees F and the refrigerator at or below 40 degrees F, and the thermometers help you decide if food is safe when the power returns. Taylor's dial thermometer reads on a 2.5 inch dial with safe zone markings. Taylor's digital model and ThermoPro's TP110 record the highest temperature reached, and ThermoPro's TP210B has two wireless sensors you can read without opening the doors.

Why the thermometer matters most in an outage

FoodSafety.gov says to keep appliance thermometers in the refrigerator and freezer, and that in a power outage they will show the temperatures to help you decide if food is safe. You cannot rely on appearance or odor alone.

FoodSafety.gov says a refrigerator keeps food cold for about 4 hours if unopened, and a full freezer keeps its temperature for about 48 hours, or 24 hours if half full, if the door stays closed. A thermometer tells you where you actually stand.

The numbers to know

• Refrigerator: at or below 40 degrees F.
• Freezer: at or below 0 degrees F.
• After an outage: if the freezer thermometer reads 40 degrees F or below, FoodSafety.gov says the food is safe and may be refrozen.
• Discard: perishable food such as meat, poultry, fish, eggs or leftovers that has been above 40 degrees F for 2 hours or more, or 1 hour if it is above 90 degrees F.

FoodSafety.gov also says to throw out perishable refrigerator food when the power has been off for 4 hours or more.

Dial, digital or wireless

A dial thermometer has no screen to go dark. Taylor's dial model reads -20 to 80 degrees F on a 2.5 inch dial with safe zone markings and is NSF listed.

A digital thermometer with a min/max memory shows the warmest temperature the appliance reached while you were away or asleep. Taylor lists that feature on its digital model, and ThermoPro lists a 24-hour max/min record on the TP110.

A wireless thermometer lets you check both appliances without opening the doors, which FoodSafety.gov says to keep closed as much as possible. ThermoPro's TP210B pairs a base station with two remote sensors.

Where to put it

Taylor says its thermometers hang or stand in the refrigerator or freezer, and its digital model also attaches with a magnet. ThermoPro says the TP110 can stand on a shelf, stick magnetically or hang from a hook. Place one where you can read it quickly when you open the door, so the door is open for as little time as possible.

Power and batteries

ThermoPro lists two AAA batteries for the TP210B base station and a built-in rechargeable battery in each remote sensor. Keep spare AAA batteries with your outage kit. Taylor's dial model has a dial rather than a screen. See our generator for refrigerator guide and battery backup guide if you want to keep the fridge running instead.

What to look for when you buy

Questions people ask

What temperature should a refrigerator be?

FoodSafety.gov says at or below 40 degrees F, and the freezer at or below 0 degrees F.

How long is food safe in the fridge without power?

FoodSafety.gov says about 4 hours if the door stays closed. A full freezer holds its temperature for about 48 hours, or 24 hours if half full.

Can I refreeze food after an outage?

FoodSafety.gov says yes if the freezer thermometer reads 40 degrees F or below, or if the food still has ice crystals or is 40 degrees F or below.

When should I throw food out?

FoodSafety.gov says to discard perishable food that has been above 40 degrees F for 2 hours or more, or 1 hour above 90 degrees F, and perishable refrigerator food after the power has been off 4 hours or more.

Sources

• Food Safety in a Disaster or Emergency (foodsafety.gov), FoodSafety.gov
• Refrigerator/Freezer Dial Thermometer (taylorusa.com), Taylor
• Refrigerator/Freezer Digital Thermometer (taylorusa.com), Taylor
• TempPro TempAir CORE TP110 (buythermopro.com), ThermoPro
• TempPro TP210B Wireless Freezer Refrigerator Thermometer (buythermopro.com), ThermoPro

Sources checked 2026-10-18.