Pre-Outage Items to Stock:
Food: At least three days' worth if you're evacuating -- two weeks' worth if you're staying home -- of non-perishable items per person. Read more on food safety during a power outage.

Manual Can and Bottle Openers: Major bummer if you can't open the food.

Water: One gallon per day, per person -- two week's worth for a home.

Medication and First-Aid Kit: Have a stocked basic kit and fill any vital prescriptions, at least 7 days' worth, such as insulin, just in case your doctor or pharmacy becomes unreachable.

Digital Thermometer: These are fairly inexpensive at most pharmacies. Get one with an LED backlight so you can read it in the dark.

Cash: No power means no ATMs or credit card machines. But life goes on and 7-11 needs to unload all that Haagen-Dazs somehow ...

Radio: Buy battery or crank-operated radios to keep up to date on news and emergency reports.

Flashlight and Batteries: Battery-up, and consider an LED flashlight, which lasts longer when charged. You can even get hand-crank models. Emergency wall-plug flashlights charge continuously so they're ready when the power goes out. Get one with a ready light so you can find it in the dark.

Whistle: So you can signal for help, if necessary.

Plastic Sheeting and Duct Tape: Seal up leaks and prevent shattered glass from blowing in.

Personal Hygiene: Wet wipes, garbage bags and toilet paper.

Tool Kit: Include a wrench or pliers for turning off utilities.

Maps: We've all come to rely on GPS, but nothing beats a map when you're out of juice.

Land-line Phone: Even if you only use a cell phone, it's a good idea to have a Plan B. Cordless phones won't work in an outage, but old-school plug telephones do, so you have a way to reach 911.

Wood: Stay warm and cook dinner if you have a wood-burning fireplace or wood stove.

Surge Protector: Keep your gadgets from power-up overload when the lights come back on.

Smoke Detector: Even if you have detectors hard-wired into the house, pick up some battery-operated backups.

Blankets: Even if it's hot outside, you need to be ready if you become wet or exposed.

Vital Documents: Have photo identification, medical info, passports, insurance policies and birth certificates in an easy-to-access place in case you need to evacuate.

Nice-to-Have Gadgets:
Phone Juicers: Get a backup battery charger for your phone. For under $100 you can get "juice packs" that keep the phone charged continuously, or chargers that can re-power your phone several times after your regular plug no longer works.

Battery Lights: Safer than candles, more convenient than holding a flashlight. Keep them plugged in, and when the power goes, they come on automatically.

Uninterrupted Power Supply (UPS): Extends the life of your computer for a bit when the grid goes down, so at least you can save your work.

Backup Generator: Pricey and bulky, but keeps basic utilities charged. Just gas it up (another good reason to keep extra fuel on hand) and run an extension cord from the generator to a power strip where you can plug in things like lights, small appliances, computers. The bigger the generator, the more it can handle.

Power Inverter: Converting power from your car's cigarette lighter or battery, these nifty tools keep larger stuff going, such as desktop computers and laptops. Great in tandem with a generator, especially if you're trying to keep your business doors open.

Books and Games: Remember those? Your Kindle will power down at some point. Don't be sad. Have a luddite story stash ready.

Also Make Sure To...
• Charge your phones, laptops, iPads and any other electronic devices that might come in handy.

• Service any emergency generators and have extra fuel on hand. Gas stations can't pump without power.

• If you own a business that houses sensitive information, prepare alternate security plans. Looting and breakins are extreme, but they do happen.

• Store extra tap water in jugs. If the water goes out, you can manually flush toilets or indulge in a sponge bath. Remember: Water heaters house a large supply of H2O that you can access from the spout at the bottom of the tank in case of emergency.

• Top off your car's gas tank and keep an extra container of fuel in the garage.

• Bring the pets inside and fill their water and food.

• Pre-load your i-thingy devices with movies and games. Can't say it enough. You will get bored. Use what you've got when you've go it, as long as you have extra chargers to fire 'em up for emergencies, too.

When the Power Goes Off:
• Turn off everything electric (except for one clock or lamp, so you know when you're back in modern times). This prevents a system overload when power returns.

• Keep the fridge closed to preserve the cold air (but start using that food after a couple hours).

• Shut all doors and windows to keep heat and A/C in for as long as possible.

• Make sure you're using treated, bottled or boiled water for drinking, washing hands, preparing food (and baby formula), brushing teeth, etc. Not all water purification systems work when the power is out. If you're not sure about your water supply, bring it to a roiling boil for 1 minute, then let cool before use. Consult the CDC's Safe Drinking Water Guidelines for more information on disinfecting water.

SOURCE: Centers for Disease Control and Prevention, Red Cross, FEMA, CNN, Popular Mechanics