Before The Power Out
1) Leave the freezer (and fridge) plugged in and turn the freezer as cold as you can.
While you might want to unplug things like your TV and computers in case of power surges you should leave the fridge and freezer plugged in and turned up so they are at their coldest until the very last minute the power goes out.
You can keep a thermometer in the freezer (and one in the fridge). While the ideal freezer temperature is 0F turn the temp as low as possible until the power outage risk is over. The fridge should be 35-38F.
Group food together - but organize your freezer
so foods like baked goods are on top, fruits and veggies below that,
then precooked foods and raw meats on the bottom. That way if your
freezer does thaw you'll be able to salvage as much as possible and wont
have to throw away food due to cross contamination.
Fill your freezer
from the top down (use baskets in chest freezers) so if there is some
flooding as much food as possible will be safe.
3) Fill the Freezer
While you can expect that the temperature in the fridge will start rising in 4 hours, a full large-sized freezer will not start to thaw for about 2 days. However, a half full freezer will start to thaw in 24 hours.
A) Move as Much as Possible to the Big Freezer
Freeze extra food in your fridge like leftovers, raw meats, milk and cheeses that you won't need immediately.
If you have more than one freezer, including the little freezer attached to your fridge move as much as possible to your largest freezer. The sheer mass of food will keep everything colder longer.
B) Freeze Water
You want to fill as much space as possible in the freezer. But when you're expecting a freezer power out you don't want to go buy more food. Instead fill empty gallon jugs, from milk for example, with water.
Or fill coffee cups of fresh drinking water and freeze, leaving room for the water to expand when it freezes. Want to leave them there all season? Place the ice cups in a sealed plastic bag in case of spills when thawed and to prevent the water from absorbing tastes and smells.
No time to freeze water? Fill your freezer with dry foods like dry pastas, bags of flour, sugar, coffee etc that you don't want to get wet if your house gets water damage, however, denser foods like meat, or even water, will stay colder longer.
4) Empty Automatic Icemakers
Empty your automatic icemaker or ice dispenser and turn off the ice maker so it doesn't melt and spill and ruin your floor while the power is out.
5) Put A Bag of Ice Cubes In the Door
A freezer bag full of ice cubes will give you a way to gauge if and how much the food in your freezer might have thawed and refroze. Store it in the door if possible as that area gets warmest.
A penny on top of an ice cube also shows if the freezer thawed but doesn't give as much detail as a full bag of ice cubes.
6) Store Food in Garbage Bags
Storing food in garbage bags or plastic storage containers means faster clean up if the freezer does thaw and all the food goes bad. At the least consider this for raw meats and anything with dairy.
Lots of prep time?
Consider making a freezer inventory so you know exactly what you have without needing to open the door.