Walk-in cooler temperature log: what to record, how often, and what the numbers mean
A walk-in cooler must keep food at 41°F (5°C) or below, and most kitchens set the dial at 35°F to 38°F to leave a margin. A walk-in freezer should hold food frozen hard, and 0°F (−18°C) is the usual target. A temperature log for either unit lists the date, the time, the reading, who took it, and a note when it is out of range. Read it at least at opening and closing, and write what you did about any reading that is high.
This guide covers the limits, where to put the thermometer, how to fill the log, how to treat a high reading and what to check when a unit drifts. For a blank sheet, see the free logs page.
What temperature should a walk-in cooler be?
The legal number is for the food, not the dial: cold TCS food (time/temperature control for safety food) must be at 41°F or below under the FDA Food Code [1]. The unit has to be colder than that so the food stays under it when the door opens, when a delivery goes in, and on a hot afternoon.
| Unit | Food limit | Typical setting | Why the gap |
|---|---|---|---|
| Walk-in cooler | 41°F or below | 35°F to 38°F | Door openings and deliveries add heat |
| Walk-in freezer | Food stays frozen | 0°F or below | Frozen food does not need to be probed, but must be hard |
| Prep cooler or cold well | 41°F or below | 34°F to 38°F | Open lids, room air, pans above the fill line |
Do not set the cooler at 41°F. A unit that averages 41°F is above it half the time. Do not set it at 32°F either: lettuce, herbs and produce freeze and spoil, and milk and eggs near the evaporator can freeze.
The Food Code does not give a freezer number for storage; it requires frozen food to be kept frozen. USDA and FDA both advise 0°F for home and commercial storage, and this is what most inspectors expect to see on a log [2].
Where to put the thermometer
One thermometer in the wrong place makes the log meaningless. A good setup:
- A thermometer inside the unit on a middle shelf, near the door side but not in the line of the door or the fan. This is the warmest spot you can read without a probe, because the door opens next to it.
- Liquid-filled or in a cup of water or glycol. Air changes fast when the door opens; liquid changes slowly. A thermometer in a small container of water reads the temperature of food, not the puff of air. Many kitchens keep a jar of water with a probe in it on each shelf.
- A display on the outside is handy, but it reads where its sensor is, usually near the evaporator, which is the coldest point. It will look better than the food really is. Check it against your inside thermometer once a week.
- A second thermometer on the top shelf for a big walk-in. Warm air rises and the coldest air is by the fan.
Calibrate every thermometer you use for the log. Fill a glass with crushed ice and a little water, stir, put the probe in without touching the glass, and wait one minute. It should read 32°F (0°C), give or take 2°F [1]. Replace or adjust any thermometer that does not, and write the date on the log.
How often to read it
- At least twice a day: opening and closing. Most health departments expect at least that, and many HACCP plans for restaurants write it as the minimum.
- Three or four times on a busy day: add one before the lunch rush and one before dinner. It is how you notice a unit that struggles under load.
- After every delivery, when a lot of warm product goes in at once.
- Anywhere with no staff at night: a data logger or a Wi-Fi sensor that writes a reading every 15 minutes catches the 2 a.m. compressor failure. It does not replace the paper log, but it lets you print the night's record.
Keep the sheet where the reader will be: on a clipboard on the door, in a sleeve, with a pen on a string. A log kept in the office gets filled in from memory.
A filled-in walk-in log
One sheet can cover several units by giving each its own column. Here is a Thursday for a restaurant with a walk-in cooler, a walk-in freezer and a bar cooler:
| Time | Cooler | Freezer | Bar cooler | Initials | Note / action |
|---|---|---|---|---|---|
| 7:00 a.m. | 37°F | −2°F | 38°F | MR | |
| 11:00 a.m. | 39°F | 1°F | 40°F | MR | After produce delivery; rechecked 11:45, 37°F |
| 3:00 p.m. | 43°F | 0°F | 39°F | JT | Door found propped. Closed; food probed 38–40°F; 3:30 p.m. unit 38°F |
| 10:00 p.m. | 36°F | −3°F | 38°F | JT |
Notice the third row. The air reading was high, the food was probed anyway, and the fix was written in a line. That one line is what separates a log from a form.
What to do with a high reading
| Reading | What it means | Do this |
|---|---|---|
| Cooler 38°F to 41°F | In range, no margin | Look for the cause (door, load, defrost). Recheck in 30 minutes. |
| Cooler 42°F to 45°F | Air is above the limit; food may still be fine | Probe the food in the middle of a few items. If 41°F or below, fix the cause and recheck within the hour. If above, treat as out of range. |
| Cooler above 45°F | Likely failure | Probe food. Move perishables to a working unit or ice. Call repair. Keep a record of the time of the last good reading. |
| Freezer above 10°F | Drifting | Check for frost, door and gasket. If food is soft or has ice crystals from thawing, treat as thawed. |
| Freezer above 32°F | Thawing | Food that has thawed may not be refrozen if it has been above 41°F for more than 4 hours. Discard what you cannot account for. |
For cold food, the rule of thumb is 4 hours total out of temperature across the day, counting the time food has been warm anywhere in the chain [1]. Your log helps here: the last good reading and the time you found the problem give the longest the food could have been warm. The steps to follow (probe, move, work out the time, decide, fix, write down) are in the cold holding temperature guide.
Why a walk-in drifts
- Door left open or a bad gasket. Put a sheet of paper in the closed door; if it slides out, the seal is worn.
- Strip curtain torn or missing on a door that opens often.
- Boxes blocking the fan or the vents. Leave space around them so air can move.
- Ice on the evaporator coil. A coil iced over means a failed defrost heater or timer, or a door left open that let in humid air.
- Dirty condenser coil. A coil furry with grease and dust runs the compressor hot and long. Clean it monthly.
- Warm food loaded. A tub of hot stock raises the unit by degrees for hours. Cool first; see the cooling log guide.
- Hot kitchen, hot day. The condenser, if outdoors or in a hot room, cannot reject heat.
- Refrigerant leak or failing compressor. If the above are fine and the unit takes longer to pull down, call a refrigeration technician.
Storing food inside so the log stays true
Where food sits changes how it behaves in an imperfect unit. The Food Code's storage order, top to bottom, goes by cooking temperature: ready-to-eat food on top, then seafood, whole cuts of beef and pork, ground meat, and poultry at the bottom [1]. The point is cross-contamination, but it also puts the highest-risk food in the coldest, lowest spot. Keep food off the floor: 6 inches is the common rule, and shelves must be clean and not overloaded.
How long to keep the log
The Food Code asks for HACCP records to be kept at least 90 days where a plan is required, and many inspectors or auditors ask for a year [1]. No national rule covers every restaurant, so ask your health department. A sheet per month, filed by date, is easy to find.
The wider set of logs, hot holding, receiving and cooling, is in the restaurant temperature log sheet guide.
Questions
What temperature should a walk-in cooler be?
The food must be at 41°F or below. Set the unit to 35°F to 38°F so it stays there when the door opens.
What temperature should a walk-in freezer be?
0°F (−18°C) or below, with food frozen hard.
How often should I log walk-in cooler temperatures?
At least at opening and closing, and add a check at midday on busy days or after a delivery.
Can I use the display on the door as my reading?
You can write it, but check it against a thermometer inside in a cup of water. The display sits by the coldest part of the unit.
What if my walk-in reads 43°F?
Probe the food. If the food is at 41°F or below, fix the cause and recheck. If it is above, move it and apply your out-of-range steps.
Is a digital data logger enough?
It can be your record if it stores and prints readings and someone reviews it daily. Most small kitchens use both: a logger for the night and a paper entry for each shift.
Do I need a log for a reach-in cooler?
Yes. Any unit holding cold TCS food belongs on the sheet, one column each.
Sources
- FDA Food Code 2022 (cold holding, thermometer accuracy, storage order, records), U.S. Food and Drug Administration
- Refrigeration and food safety, USDA Food Safety and Inspection Service
Related: all food safety guides.