During a Power Outage
Keep refrigerators and freezers closed to help them stay cold inside.
An unopened refrigerator will stay cold for about four hours. An unopened full freezer will hold its temperature for about 48 hours (24 hours, if it's half full).
Dry or block ice can help, if you stocked up before the power cut. Figure on 50 pounds of dry ice to keep an 18-cubic foot, fully stocked freezer cold for two days.
If you plan to eat refrigerated or frozen meat, poultry, fish, or eggs while they're still at safe temperatures, cook them thoroughly.
Wash fruits and vegetables with water from a safe source before eating.
For formula-fed infants, use prepared, canned baby formula that requires no added water, if possible. For concentrated or powdered formulas, used bottled water if the local water source might be contaminated.
After a Power Outage
If you kept an appliance thermometer in your freezer, check it. If it's 40 degrees Fahrenheit or below, the food is safe and may be refrozen.
No thermometer in the freezer? Check each package of food. Look for ice crystals - a sign that the food is still safe -- or items that are 40 degrees Fahrenheit or colder. Don't just go by smell or appearance.
Refrigerated foods should be safe as long as the power is out for no more than four hours.
Discard any perishable foods (such as meat, poultry, fish, eggs, or leftovers) that have been above 40 degrees Fahrenheit for two hours or more.