You may never think about the temperature when your refrigerator and freezer are operating properly, but the settings chosen for each compartment have a major impact on food safety. Many fridge and freezer units do not have actual temperatures listed on the dial, so a thermometer suitable for each area helps you make sure your dialed-in selections are ideal for cold food storage.
You need a refrigerator/freezer thermometer to determine the current temperature range in both your fridge and freezer -- otherwise you won't know whether to adjust the temperatures to warmer or cooler settings. These thermometers are designed to handle the extreme cold; do not use a regular outdoor thermometer or oral thermometer, because they may not provide accurate readings. Keep one of these thermometers inside both the refrigerator and freezer at all times -- this way, you'll have a good idea whether chilled and frozen items are still safe to eat during or after a power outage. Some of these thermometers have a curved hanger at the top so you can hang them from a refrigerator rack. Keep the thermometer near the center of either the fridge or freezer for long-term readouts.
Place the refrigerator thermometer in a glass of room-temperature water, and then set the glass near the middle of the refrigerator -- not near the door, or near walls where it may be exposed to heat from a light bulb, fan or motor. After five to eight hours, check the thermometer to get an accurate temperature reading.
Sandwich the refrigerator/freezer thermometer between frozen food items somewhere near the middle of the freezer for an accurate reading. Wait five to eight hours, and then check the thermometer readout.
The optimal temperature range for the refrigerator is 34 to 40 degrees Fahrenheit to keep food safe and unfrozen. If your thermometer reading is outside of this range after the temperature test, adjust the temperature settings. Look for a dial with numbers on it; some models may say "cooler" or warmer," or offer similar wording. The dial indicators mean different things on different models; for instance, "10" may be the warmest setting, or it could mean the coolest. Consult your owner's manual to be sure you're adjusting the setting in the right direction. The perfect temperature range for a freezer is at or slightly below zero degrees F, and never more than 2 degrees F. Adjust the freezer settings as necessary. After making adjustments to either the freezer or refrigerator, check the thermometer's temperature readout after another five hours, repeating the adjustment process until the reading is in the ideal range.
During a power outage, food that stays at or below 40 degrees Fahrenheit is still safe to use. Keep the refrigerator and freezer doors closed to help keep the cool air in. After grocery shopping or returning from a restaurant with leftovers, place the items that require refrigeration or freezing in the refrigerator or freezer within two hours -- one hour or less if the temperature outside is 90 degrees F or greater. Keep in mind that your car may be even hotter than the air temperature, so put those foods away as quickly as possible during hot weather.