Freezer temperature log: what to record, how often and what to do when it creeps up

A freezer temperature log records that your walk-in or reach-in freezer stayed at 0°F (-18°C) or colder, the standard for keeping frozen food safe and good. Each row needs the date, the unit, the reading, the time, who took it and what you did if it was high. Check at least once at opening and once at close, longer if the unit is old or busy. This page covers the number and where it comes from, where to put the thermometer, a filled-in sheet and what to do with the food when a freezer fails.

If you want a blank sheet to print, the free sheets are on the logs page. Below is how to fill one in so it holds up when an inspector reads it.

What temperature a freezer should hold

The target is 0°F (-18°C) or below. The USDA gives that number for keeping food safe, since bacteria stop growing at that temperature and quality stays good [1]. The FDA Food Code is less specific than most people think. It requires frozen food to be kept frozen, and it sets numbers for cold holding at 41°F, but it does not write a single freezer setpoint into the rule [2]. Your health department or your HACCP plan fills that gap, and 0°F is the number almost all of them use.

So the sentence in your plan should read: "Freezers are kept at 0°F or below; frozen food must be solid." Use that as the critical limit, and write down what you do when it fails.

Note that "act at" is a working number: the freezer is warmer than ideal, so look into it before the food softens.

Where to put the thermometer

Most freezer problems are missed because the thermometer is in the wrong place. The Food Code requires a temperature-measuring device in refrigerated units that shows the air temperature, readable from outside and accurate to within 3°F [2]. Use these placement rules:

• Put it where the warmest air is. In a walk-in that is near the door, and in a reach-in on a top shelf near the door gasket. A thermometer next to the evaporator fan will always read colder than the rest of the box.
• Place it in the middle of the product, not against the wall. A cup of antifreeze or glycol with the thermometer in it reads like food does, and swings less when the door opens. A lot of kitchens use a sealed bottle of water with a little salt or glycol for the same reason.
• Read it without opening the door. An external digital display or a dial through a window gives a fair reading without letting warm air in.
• One per unit. Not one for the whole kitchen.
• Check it against a calibrated probe now and then. The thermometer calibration log guide shows how.

How often to check

There is no federal number of checks. Most plans use twice a day: when the first person opens and when the last person closes. A few other points where a quick look helps:

• After a delivery, when the door was open for a long time.
• After a defrost cycle on an older unit. Many freezers run a defrost every 6 to 12 hours and the air warms for a short time. If your log always shows a high reading at 6 a.m., the defrost cycle is likely the cause.
• After a power cut, however short.
• When the compressor sounds different, or when you see frost on the door gasket or ice on the floor.

An electronic data logger or a wifi sensor that records every few minutes is better than a paper check, and many health departments accept its printout in place of a written reading. If you use one, save the printout and still write down a daily review: the log is only useful if somebody looks at it [3].

A filled-in freezer log

Keep the columns short: date, unit, time, reading, initials, action. Here are rows from a week with one problem:

The Tuesday and Wednesday rows are what make the log valuable. Each shows a drift caught, a cause and a fix. A sheet where every box says -2°F for six months looks invented, and an inspector will ask to see the thermometer.

What to do when the freezer is too warm

Treat a reading above 0°F as a prompt to look, and a reading above 10°F or food that is no longer hard as a failure. Work through it in this order:

1. Recheck. Close the door, wait 10 minutes and read again. A single warm reading after a delivery is common.
2. Check the cause. Door ajar or not sealing, a gasket with a gap, heavy frost on the coil, a fan not running, a recently loaded warm item, a defrost heater stuck on, or a compressor tripping.
3. Look at the food. Is it hard? Do you see ice crystals, softening or liquid in the packaging? Thawed food that feels cold as a refrigerator (41°F or below) can be handled as refrigerated product: cook it within the day or according to your health department. Food that has sat above 41°F for 4 hours or more has run out the Food Code's time limit without temperature control and should be discarded [2].
4. Move product to a working freezer if the fix will take a while. Keep the door shut meanwhile: a full freezer holds cold for many hours, an empty one for far less.
5. Write it down in the Action column: what you found, what you did, and who you called.
6. Do not refreeze raw meat or fish that fully thawed and warmed. Product that still has ice crystals and stayed at 41°F or below may be refrozen with some loss of quality [1]; when in doubt, ask your health department.

Never "fix" a log after the fact. If the freezer was warm and you did not look for two days, write the days you did look.

Common causes of a warm freezer

• Door habits. Propped doors during a delivery or a prep rush let in warm, moist air that ices up the coil.
• Overstocking. Boxes stacked against the evaporator block the airflow. Leave a gap, and keep product off the floor and away from the fan.
• Worn gaskets. A gasket that does not grip a dollar bill in the door should be replaced.
• Frost build-up. A heavy layer on the coil or the walls means the defrost cycle is failing or the door has been open often.
• Warm loading. Putting hot or room-temperature food in raises the air temperature. Cool food first; see the cooling log guide.
• A dirty condenser. Dust and grease on the coil make the compressor run hot and long. Clean it monthly.

Thawing and the freezer log

Your freezer log shows storage. The next link in the chain is thawing, which the Food Code allows in four ways: under refrigeration at 41°F or below, under running water at 70°F or below for the time it takes to prep, in a microwave as part of immediate cooking, or as part of the cooking process [2]. Thawing on the counter is not on the list. For raw fish that will be served uncooked, the freezer is itself the control, with a time and a temperature to kill parasites; the sushi guide covers it: HACCP plan for a sushi restaurant.

Where it sits in a HACCP plan

Frozen storage is usually a prerequisite program in a HACCP plan, not a critical control point, because the hazard of a short drift is low compared with cooking or cooling. Still, you write it down as a standard: limit 0°F, monitoring twice a day, corrective action as above, record the freezer log. The critical control points guide explains the split, and the walk-in cooler temperature log shows the matching sheet for the cold side. Keep these with your other temperature records for at least 90 days, and longer if your health department asks [2].

Questions

What temperature should a restaurant freezer be?

0°F (-18°C) or below, with frozen food hard to the touch [1].

Does the health department require a freezer temperature log?

Not every one does, but many ask to see temperature records, and a HACCP plan that mentions freezers is expected to have them. A log is the simple way to show the freezer works.

How often should I record the freezer temperature?

Twice a day is the usual standard, at opening and closing, plus any time the unit has a problem.

What do I do if the freezer is above 0°F?

Recheck after closing the door, find the cause, check whether the food is still solid and write what you did. Above 10°F or soft food is a failure.

Can I use a logger instead of writing readings?

Often yes, if your inspector accepts the printout, and you review it daily and sign the review.

How do I read the freezer temperature?

From a thermometer placed near the door, in a cup of glycol or antifreeze, read without opening the door.

Where do I get a freezer log?

Use the columns above or the free sheets on our logs page. More in our food safety guides.

Sources

1. Freezing and food safety, USDA Food Safety and Inspection Service
2. FDA Food Code 2022 (3-501.13 thawing, 4-204.112 temperature measuring devices, 8-201 records), U.S. Food and Drug Administration
3. Refrigeration and food safety, USDA Food Safety and Inspection Service

Related: all food safety guides.