This Weekend Will Likely Be the Hottest of the Summer

Boston may see record-breaking temperatures, but the real star of the weekend is the humidity.

boston skyline

Photo via Lise Gagne/iStock

Hope you enjoyed this morning’s temperate weather! As you’re clinging desperately to your window AC, cleaning melted ice cream off yourself, and sweating out liquid faster than you can drink this weekend, you’ll need some fond memories of bygone temperatures to pull you through.

The National Weather Service has officially issued an excessive heat warning for nearly all of Massachusetts, starting Friday at noon and remaining active until 8 p.m. Sunday. Forecast temperatures are inching close to triple digits, and if we hit 100 or higher on Saturday, we’ll beat out July 20, 1991 for the hottest July 20 on record. Temperatures have only reached 100 degrees 25 times since Boston’s weather records began in 1872.

But according to WBUR’s daily forecaster, meteorologist Dave Epstein, it’s the humidity that’s really going to make this a weekend to remember.

“You’ll essentially be experiencing what you’d experience on an island,” Epstein says. But he’s not talking about mai tais, coconut bras, and beachside luaus. Oh no. He’s talking about the tropical air that’s heading for our city right now, which is going to boost this weekend’s humidity to “about as high as we ever see in Southern New England,” he says.

Here’s the thing: We’re getting island weather, but we are, in fact, not on an island. Thanks to the land that attaches us to the rest of the continent, that steamy, steamy air will be trapped in the city, making Boston a hot, damp, and probably smelly convection oven instead of a tropical oasis.

So while the thermometer might read a meager 98-99, Epstein says that the heat index—a measurement that takes both the heat of the air and the humidity into account—will certainly be over 100, potentially reaching 105-108.

“The body can’t cool itself with that amount of moisture in the air,” he says, ominously. “Sweating doesn’t work.”

Epstein suggests that if you have to go outside on Saturday or Sunday, do it before 9:30 a.m. After that, cuddle up to your air conditioner, or visit one of the city’s designated cooling centers. And definitely don’t leave anything in the car, which will heat up to a deadly temperature for much of the day.

While most local meteorologists have their eyes on Saturday as peak heat, Epstein believes it’ll be a coin toss between which day actually ends up hotter. He is pretty confident, however, that this will be the hottest weekend we see this summer, possibly sealing 2019’s place in the record books as the hottest July Boston has ever seen.

It will be miserable. But at least it will be short-lived. By the start of next week, Epstein says, temperatures will drop back down to the 70s and 80s.

Here’s hoping we don’t melt before then!