How to Prepare for a Long Power Outage: Hours, Days and Weeks

Hours, days or weeks: what you are planning for

Hours. A storm takes down a line or a substation trips. The lights come back the same day. You need a flashlight, a charged phone and the sense to leave the fridge shut.

Days. An ice storm, a hurricane or a grid failure in extreme weather. In February 2021 more than four million Texas customers lost power in sub-freezing temperatures, many for several days; the state's final count was 246 deaths, most from hypothermia and carbon monoxide poisoning, and millions were under boil-water notices afterwards. This is the case to prepare for, because it is the one that hurts people.

Weeks. A major hurricane, an earthquake, a failure of the grid itself. On April 28, 2025 the whole of mainland Spain and Portugal went dark in seconds: trains stopped, traffic lights, card terminals, cash machines and most mobile networks failed, and power took about ten hours to return. That outage was short; the lesson planners drew from it is that a longer one would leave tens of millions with no way to pay, call or travel. The British and Canadian preparedness campaigns cite it by name. For a two-week outage you need the home supply on the basics page plus the items at the end of this one.

Light and power

LED flashlights and headlamps run for days on a set of batteries; keep spares and a hand-crank light. For phones and radios, a power bank per person; a 20,000 mAh bank recharges a phone three or four times. A small solar panel or a hand-crank charger tops them up over a long outage. Battery power stations (large lithium packs sold for camping) will run a CPAP, a router or a small fridge for a night and recharge from the car or a panel; they are the safe alternative to a generator for most households.

If you run a portable generator, these rules are not optional. Outdoors only, at least 20 feet from any door, window or vent, exhaust pointed away from the house, never in a garage, porch, carport or basement even with doors open; the Consumer Product Safety Commission counts about a hundred deaths a year from generator carbon monoxide in the United States, many in attached garages with the door up. Plug appliances into the generator with heavy outdoor extension cords, or have an electrician fit a transfer switch; never plug a generator into a wall outlet, which can electrocute a line worker and start a fire. Keep a working carbon monoxide alarm on every level of the house, with fresh batteries. If it sounds, get everyone outside and call for help from there.

Staying warm, staying cool

Cold. Choose one room, small and on the sunny side if you can, and move everyone into it. Close its door, hang blankets or towels over the windows and over the doorway, and put rolled towels along the gaps. Wear layers and a hat indoors, eat and drink regularly, and sleep together under shared blankets. Open the cabinets under sinks and let faucets drip to keep pipes from freezing; if the house will be below freezing for long, shut the main valve and drain the lines. Hypothermia creeps up: confusion, slurred speech and drowsiness in a cold person are an emergency.

What not to do: never heat a room with a gas oven, a charcoal grill, a camp stove or a patio heater. They produce carbon monoxide and they kill people in every long winter outage. The only safe indoor heaters are those rated for indoor use, run with a window cracked and a carbon monoxide alarm in the room.

Heat. In a summer outage the danger reverses. Stay on the lowest floor, close blinds on the sunny side, open windows at night, wet cloths on the neck and wrists, drink more than you think you need, and avoid cooking indoors. Check on older people twice a day; heat kills more Americans than any other weather. Never leave anyone, or a pet, in a parked car. If your home is above about 90 degrees for long and someone is frail, go to a cooling center or a friend's house with power.

Water

Pumps need electricity. City water pressure may hold for a while from tanks and towers and then fall; a private well stops at once. When a storm is forecast, fill the bathtub (for flushing and washing) and clean containers (for drinking), and keep the gallon-a-day supply from the basics page on hand. After an outage, treatment plants may issue boil-water notices; boil for one minute, or use 8 drops of 6 percent household bleach (6 drops of 8.25 percent) per gallon and wait 30 minutes. Your water heater holds 30 to 50 gallons of clean water; turn off its power or gas before you drain it.

Food

A closed refrigerator keeps food safe about four hours; a full freezer about 48 hours, half-full about 24. Keep appliance thermometers in both so that you know rather than guess: food that has been above 40 degrees Fahrenheit for more than four hours goes out, however it looks or smells. Group frozen food together so it keeps itself cold, and move milk and leftovers into a cooler with ice if the outage will run long. Eat from the fridge first, then the freezer, then the shelf. Cook outdoors only, on a grill or camp stove, never inside. The non-perishable, no-cook food on the basics list is what you fall back on.

Medicine and medical equipment

Refrigerated medicines such as insulin keep for days in a cooler with ice packs, kept cool but not frozen; most insulin is safe at room temperature for up to 28 days, check the maker's leaflet. Keep a seven-day supply of prescriptions and ask about 90-day fills. If someone in the house depends on powered equipment (oxygen concentrator, CPAP, dialysis, a ventilator, a powered wheelchair), register with your utility's medical priority program now, keep the device's own battery backup charged, know how many hours it gives you, and have a plan to reach a hospital or a shelter with power before it runs out. A battery power station sized for the device is the single best purchase such a household can make.

Phones, information and money

Mobile towers usually have a few hours of battery backup, sometimes generators; expect service to degrade over the first day. Text instead of calling, turn down screen brightness and switch off what you do not need to stretch the battery, and download offline maps of your area now. A battery or hand-crank AM/FM and NOAA weather radio is how you will get official information when the towers are gone. Keep cash in small bills: card terminals, cash machines and fuel pumps all stop with the power, as Spain and Portugal found in a single afternoon. Keep the car's tank above half for the same reason.