Keep the refrigerator and freezer doors closed as much as possible.
A refrigerator will keep food cold for about 4 hours if you keep the door closed.
A full freezer will keep its temperature for about 48 hours (24 hours if half-full)
If the power is out for an extended period of time, buy dry or block ice to keep the refrigerator as cold as possible. Fifty pounds of dry ice should keep a fully-stocked 18-cubic-feet freezer cold for two days.
When the Power Is Restored:
Check the temperature in the refrigerator and freezer. If the thermometer reads 40° F or below, the food is safe.
If no thermometer was used in the freezer, check each package. If food still contains ice crystals, it’s safe.
Discard any perishable food (such as meat, poultry, fish, soft cheeses, milk, eggs, leftovers and deli items) that have been kept in a refrigerator or freezer above 40° F for two hours or more.