Keep extra ice in your freezer and freeze bottles of water.
Buy extra bags of ice to keep in your freezer to help maintain its temperature, and to use later if you have to transfer your food into a cooler.
If your freezer has an ice maker, empty the ice cubes into gallon-sized storage bags each time the tray is full.
You can also consider buying dry ice in the event of a power outage. Fifty pounds of dry ice will keep a closed freezer or a cooler cold for between 18 and 24 hours. Just be sure to handle it safely and avoid touching it with your bare hands.
The USDA also recommends keeping bottles of water in your freezer. Not only will this help keep frozen food cold longer, but also you will also have a supply of fresh drinking water in case your water supply becomes contaminated.
If water bottles are in short supply, which often happens when a storm is approaching, freeze fresh water in clean, quart-sized storage bags or food-safe plastic containers.