Welcome to Hell Week: New York City is about to experience a truly terrible heat wave, with temperatures topping out at over 100 degrees.

“We’re entering a heat emergency,” Mayor Bill de Blasio said during a press conference on Wednesday.

According to the National Weather Service, which has issued an excessive heat warning for the city, the worst of the heat wave will start on Friday and continue through the weekend. Temperatures are expected to be uncomfortably high—in the mid 90s to over 100 degrees—and the heat index will make it feel like it’s anywhere from 105 to a whopping 115 degrees. Temperatures will hit their peak from 2 to 5 p.m., according to the NWS. (And you know what that means: It will feel even hotter underground.)

In short: Prepare to be extremely not chill for the next few days (unless you’re one of those people who actually enjoys summer, in which case, move right along).

The city’s Office of Emergency Management has already declared a heat emergency in advance of the worst part of the week, and announced that the city’s cooling centers will be open from Wednesday until Sunday. The Department of Social Services has also issued a “Code Red” alert for the city’s homeless, and will ensure that unsheltered persons are able to access shelters and drop-in centers throughout the city—the Coalition for the Homeless has a list of those.

“Stay indoors to the maximum extent possible, stay out of the sun,” de Blasio said during the presser. “If you don’t need to be outside for work or for travel, stay indoors. The more time you’re out in that extreme heat, the more time you’re out in the sun, the more challenges you’ll face.”

De Blasio also signed an executive order that requires office buildings to set their A/C to 78 degrees, the better to stave off chances of a power outage due to overwhelming the electrical grid. The order applies only to offices, not residential spaces or ground-floor retail and other public uses.

The city has a list of other ways to stay cool in extreme heat—and we also have some suggestions for how to prepare.

Get into air conditioning.

If you don’t have A/C in your apartment, you can still take advantage of the many spots around the city that do have free air conditioning—not just the approximately 500 city-mandated cooling centers, but transit hubs, shopping malls, and other sites where you can linger for a few hours without arousing suspicion. Cooling centers will likely have extended hours; stay tuned for more details.

If you do have A/C, the city asks that you keep it set at 78 degrees, the better to ensure that the electrical grid doesn’t get overloaded (but if it does, and there’s a blackout, read on to find out how to prepare for that.)

Take a dip.

There are dozens of free public pools throughout the five boroughs—some Olympic-sized, some intended just for wee kiddos, and some that are even cooler thanks to NYC Parks-funded renovations. They’ll have extended hours—from 11 a.m. to 8 p.m.—from Friday to Sunday.

If you want a slightly fancier experience, you can pay for a day pass to one of the city’s coolest rooftop pools. And, of course, there are city beaches, which will also have extended hours—you’ll still get sweaty and gross and covered in sand, but it’s better than being sweaty and gross in your apartment.

You may be tempted to open a fire hydrant—but there’s a right way to do that, which involves little more than asking your local fire house for a spray cap.

New Yorkers, it's going to be HOT this week. Cool off by requesting a spray cap from your local firehouse and enjoy the shower! pic.twitter.com/0zrcKGxeln — NYC Mayor's Office (@NYCMayorsOffice) July 17, 2019

Prepare for a blackout.

Just in case! Energy use throughout the city is higher in the summer thanks to the constant running of air conditioners—which can lead to power outages both large and small. Keep emergency supplies on hand, and know what to do if there is a widespread blackout—we’ve got you covered.

Check on your neighbors.

“In New York City, most heat-related deaths occur after exposure to heat in homes without air conditioners,” according to the city. Be sure to check in on neighbors and friends who may be especially vulnerable—seniors, those with mobility or access issues, or small children—and offer your A/C, if possible.

Stay hydrated.

Drink water, and lots of it, especially if you have to be outside for any prolonged period of time. Other liquids are okay too, and though we know the temptation to stay on the beach with a beer or a nutcracker is great, alcohol is definitely not hydrating. Have water early and often, even if you don’t feel thirsty. DEP will be placing portable water fountains in busy parts of town throughout the weekend.