Temperatures in Boston for the week peaked with a heat index in the triple digits on Wednesday — but residents may not see a real cool off until Friday.

“Unfortunately, summers are hotter and hotter in Boston, and so this is becoming more of a regular experience that our residents and our businesses and everyone around the city has to have the muscle memory of how to get through a heat wave,” said Mayor Michelle Wu on Wednesday.

“On the city side, we want to make sure, first of all, that people are safe, there are resources available, and everybody knows it’s coming. Check on your neighbors, plan ahead, hydrate, hydrate, hydrate.”

Wednesday reached a high of 95 degrees in Boston and a heat index of 100 degrees, according to the National Weather Service. Boston, along with a wide stretch across the New England coast, will fall under a NWS heat advisory through Thursday evening.

The typical seasonal high is around 83 degrees, according to NWS, though the record for July 16 was set at 99 degrees and last year reached 95 degrees as well.

Thursday is forecasted to see similar muggy, tropical weather.

“Expect pretty much a repeat of today,” said NWS meteorologist Matthew Belk. “We’re looking at high temperatures, maybe a little bit cooler due to a sea breeze, 87 degrees. By the time you get out towards MetroWest, closer to 90 degrees. But it’ll still be humid.”

Thursday may also see showers and thunderstorms throughout the day, forecasts show.

Bostonians may get some relief on Friday, with high temperatures expected to drop into the low 80s.

“We do expect more normal temperatures Friday,” said Belk. “But as far as the humidity goes, that’s probably going to be slower to decline, a bit more like Friday afternoon, Saturday.”

Wu said there are “plenty of places where you can have fun, stay cool and still be out and about,” noting the city’s 80 splash pads and several BCYF and state-run pools. BCYF Cooling Centers and Boston Public Library locations are also open to those looking to come inside and escape the heat during the emergency.

“The number one thing is, just remember to take care of yourselves and take care of your neighbors,” said Wu. “The symptoms can come on quite quickly, when it comes to heat related illnesses. So just have that in mind and be ready.”

More information on the resources and tips for the heat emergency can be found at boston.gov/heat.