NYC Blackout? Preparation Is Key.

Let’s say it’s Friday night and you’re beating the 100-degree heat in New York City, watching Netflix while sitting in the direct path of a fan or an air-conditioner, when everything goes dark.

The last major blackout in the city happened almost 20 years ago. But these days, as global warming means hotter temperatures, the city’s power grid will be put to the test more and more.

“We are witnessing what is fast becoming our new normal — a direct repercussion of climate change,” said Zach Iscol, New York City’s commissioner of emergency management, referring to more frequent extreme weather events, like dangerous heat.

So if a power outage happens, what should New Yorkers do?

In Advance of a Blackout

Preparation is key, Mr. Iscol said: “What have you done so you’re not fumbling around in the dark?”

The commissioner rattled off a list of things to do before an emergency strikes that included refreshing flashlights with new batteries; stocking bottled water; and organizing contact and health information for everyone in the household, including pets.

His office also has a list of additional items it recommends for a “go-bag,” including cash, toiletries, portable cell phone chargers and also games for children.

But the most important thing New Yorkers should do is register with Notify NYC, the city’s public messaging system, by calling 311, signing up for email alerts on the website or downloading the app, Mr. Iscol said. Those with life-sustaining equipment like dialysis machines should register with ConEd or PSE&G, so they will have priority in getting their power restored.

Everyone should have a “grid-down” protocol, said Jason Charles, a former New York City firefighter who posts survival tips as the Angry Prepper on social media. Supplies should be customized to meet certain residential and health conditions.

He recommended that “grid-down” gear include:

• a battery pack and individual batteries

• fully juiced external chargers

• extra medication (diabetics should have cooling packs for their insulin)

• charging cords

• a portable, AM/FM radio

• nonperishable food

• first aid kit

What to do when a blackout happens

If the power goes out, rule No. 1, Mr. Charles said, is to know the location of their go-to flashlight, as it will lead them to everything else they need.

New Yorkers should have enough water to get them through 48 hours, roughly a gallon a day per person, he added. People in high rises should fill up their tubs.

If you have a cooler, load it with ice and transfer perishables. If you don’t, avoid frequent visits to the fridge.

Solar-powered products that can charge up during the day include a lantern and a power bank, which is a sturdy-looking box containing various outlets for plugging items into, like a fan. There are also solar-powered fans these days.

Disconnect appliances that might turn on automatically once power returns so that the system is not overloaded, Mr. Iscol said.

Depending on the severity and duration of the blackout, the commissioner said, the city will provide transportation to designated cooling centers, powered by generators, for the city’s most vulnerable.

What Not to Do

“Don’t go on the roof,”said Mr. Charles, who once responded to a call where a man at a blackout party had fallen into darkness.

Only use candles as a last resort and don’t leave them unattended, both experts said. Mr. Charles suggested that after candles are secured in holders, they should be placed in a container of water, in case they fall over.

And don’t sneak into a city pool if it’s closed, Mr. Charles advised. But options like keeping public pools open later could happen in the future, Mr. Iscol said. In emergencies like this, “everything is on the table.”