A storm knocks the power out. Suddenly you have no heat, no lights — and no juice to keep the refrigerator and freezer cold (unless you have a backup generator). How long will the food keep? And how can you make it last as long as possible?

First, keep the refrigerator and freezer doors closed. Every time you open them you let out the cold — and without power, you can’t get that cold back.

As a general rule of thumb, if the power’s been out for less than four hours — and you haven’t opened the door — the food in the fridge is probably still good, according to the U.S. Food and Drug Administration (FDA). If you’re not sure if a food is still safe, consult the handy chart from the United States Department of Agriculture (USDA) at the bottom of the page.

If the inside of the fridge has been at more than 40 degrees F for more than two hours (check it with an appliance thermometer), throw the food out.

How long food in the freezer lasts depends in large part on how much food is in there. A full freezer gives you about 48 hours, and a half-full freezer, about 24 hours, according to the FDA. Again, this assumes you haven’t opened the door. If the freezer stays at or below 0 degrees F, the food is okay.

If you have access to the roads and to a store that stocks ice, buy some dry or block ice (assuming it’s not sold out) to keep the refrigerator as cold as possible if the power is going to be out for a prolonged period of time. Fifty pounds of dry ice should keep an 18-cubic foot fully stocked freezer cold for two days according to USDA.

Before the next storm

If there’s a big storm coming and you know the power might go out, here are a few steps you can take in advance to prepare your fridge and freezer:

1. Move foods from the fridge to the freezer. Do this for items you won’t need immediately. They’ll keep longer in the freezer. Bonus: A full freezer will keep everything in it cold longer than a half-empty freezer.

2. Prepare a cooler. Stock up on ice and have a large cooler handy. If it looks like the power will be out for more than four hours, put the ice in the cooler as well as the foods you most want to save (like that expensive piece of steak or block of gourmet cheese).

3. Stock the freezer with dry or block ice. An alternative: Freeze containers of water.

4. Keep food out of water’s way. In case of a flood, store nonperishable food items, along with your bottled water, on a high shelf. If food comes in contact with the water, you need to discard if it’s not in a waterproof container. Screw-caps, snap lids, and cardboard boxes are not waterproof.

5. Make sure you have a non-electronic can opener. This might seem obvious, but if the power does go out, you’ll need a way to open all those cans or you could find yourself with food all around you but nothing to eat.

Refrigerator Foods
When to Save and When to Throw It Out
FOOD Held above 40 °F for over 2 hours
MEAT, POULTRY, SEAFOOD | Raw or leftover cooked meat, poultry, fish, or seafood; soy meat substitutes
Thawing meat or poultry Discard
Meat, tuna, shrimp, chicken, or egg salad Discard
Gravy, stuffing, broth Discard
Lunch meats, hot dogs, bacon, sausage, dried beef Discard
Pizza, with any topping Discard
Canned hams labeled "Keep Refrigerated" Discard
Canned meats and fish, opened Discard
CHEESE | Soft Cheeses: blue/bleu, Roquefort, Brie, Camembert, cottage, cream, Edam, Monterey Jack, ricotta, mozzarella, Muenster, Neufchatel, queso blanco, queso fresco
Hard Cheeses: Cheddar, Colby, Swiss, Parmesan, Provolone, Romano Safe
Processed Cheeses Safe
Shredded Cheeses Discard
Low-fat Cheeses Discard
Grated Parmesan, Romano, or combination (in can or jar) Safe
DAIRY | Milk, cream, sour cream, buttermilk, evaporated milk, yogurt, eggnog, soy milk
Butter, margarine Safe
Baby formula, opened Discard
EGGS | Fresh eggs, hard-cooked in shell, egg dishes, egg products
Custards and puddings Discard
FRUITS | Fresh fruits, cut Discard
Fruit juices, opened Safe
Canned fruits, opened Safe
Fresh fruits, coconut, raisins, dried fruits, candied fruits, dates Safe
SAUCES, SPREADS, JAMS| Opened mayonnaise, tartar sauce, horseradish Discard if above 50 °F for over 8 hrs.
Peanut butter Safe
Jelly, relish, taco sauce, mustard, catsup, olives, pickles Safe
Worcestershire, soy, barbecue, Hoisin sauces Safe
Fish sauces (oyster sauce) Discard
Opened vinegar-based dressings Safe
Opened creamy-based dressings Discard
Spaghetti sauce, opened jar Discard
BREAD, CAKES, COOKIES,PASTA, GRAINS | Bread, rolls, cakes, muffins, quick breads, tortillas
Refrigerator biscuits, rolls, cookie dough Discard
Cooked pasta, rice, potatoes Discard
Pasta salads with mayonnaise or vinaigrette Discard
Fresh pasta Discard
Cheesecake Discard
Breakfast foods — waffles, pancakes, bagels Safe
PIES, PASTRY | Pastries, cream filled Discard
Pies — custard, cheese filled, or chiffon; quiche Discard
Pies, fruit Safe
VEGETABLES | Fresh mushrooms, herbs, spices Safe
Greens, pre-cut, pre-washed, packaged Discard
Vegetables, raw Safe
Vegetables, cooked; tofu Discard
Vegetable juice, opened Discard
Baked potatoes Discard
Commercial garlic in oil Discard
Potato Salad Discard

Frozen Food
When to Save and When To Throw It Out
FOOD Still contains ice crystals and feels as cold as if refrigerated Thawed.
Held above 40 °F for over 2 hours
MEAT, POULTRY, SEAFOOD | Beef, veal, lamb, pork, and ground meats

Poultry and ground poultry Refreeze Discard
Variety meats (liver, kidney, heart, chitterlings) Refreeze Discard
Casseroles, stews, soups Refreeze Discard
Fish, shellfish, breaded seafood products Refreeze. However, there will be some texture and flavor loss. Discard
DAIRY | Milk
Refreeze. May lose some texture.

Eggs (out of shell) and egg products Refreeze Discard
Ice cream, frozen yogurt Discard Discard
Cheese (soft and semi-soft) Refreeze. May lose some texture. Discard
Hard cheeses Refreeze Refreeze
Shredded cheeses Refreeze Discard
Casseroles containing milk, cream, eggs, soft cheeses Refreeze Discard
Cheesecake Refreeze Discard
FRUITS | Juices Refreeze Refreeze. Discard if mold, yeasty smell, or sliminess develops.
Home or commercially packaged Refreeze. Will change texture and flavor. Refreeze. Discard if mold, yeasty smell, or sliminess develops.
VEGETABLES | Juices Refreeze Discard after held above 40 °F for 6 hours.
Home or commercially packaged or blanched Refreeze. May suffer texture and flavor loss. Discard after held above 40 °F for 6 hours.
BREADS, PASTRIES | Breads, rolls, muffins, cakes (without custard fillings)

Cakes, pies, pastries with custard or cheese filling Refreeze Discard
Pie crusts, commercial and homemade bread dough Refreeze. Some quality loss may occur. Refreeze. Quality loss is considerable.
OTHER | Casseroles—pasta, rice based Refreeze Discard
Flour, cornmeal, nuts Refreeze Refreeze
Breakfast items — waffles, pancakes, bagels Refreeze Refreeze
Frozen meal, entree, specialty items (pizza, sausage and biscuit, meat pie, convenience foods) Refreeze Discard

Sydney is a self-proclaimed social media addict and a recent grad of the University of Georgia with a B.A. in Journalism. She spent two summers in New York interning with Cosmopolitan.com and iVillage, where one of her articles garnered the most traffic on the site. In her free time, when she’s not pinning DIY projects or fostering golden retrievers, she looks forward to Christmas so she can add to her 25 days of baking blog. Her favorite safety tip: Don’t text and drive — no text is worth it!