It's likely the start of the region's first heat wave of the year, and many communities, including Boston, have declared a heat emergency for the next two days. The temperature is expected to reach well into the 90s, with the heat index nearing 100 degrees.
For many people, it's a time to take refuge in the cool indoors, by air conditioners or at malls or movie theaters. But some are looking to keep enjoying summer outdoors — no matter how high the mercury rises.
At Wollaston beach in Quincy, Steve Wiejkus said he plans to get in his daily six-mile walk, even as the pavement sizzles. He doesn't want to miss a sunny July day.
"This weather goes by too quick," Weijkus said. "Before we know it, we're going to be in the late fall. ... So try to enjoy all the time we can with this good weather. It's a gift."
Weijkus' attitude about the heat will likely come in handy in the future, as scientists suggest we'll experience a lot more 90-plus degree days because of climate change. A report from Climate Ready Boston predicts the city could see as many as 40 days every summer where the thermometer reaches 90 degrees or higher, up from an average of 11 days.
By 2050, the typical summer in Boston could feel as hot and sticky as a summer in Washington D.C.
To deal with this week's heat, the Department of Conservation and Recreation is expanding hours at state-run pools, beaches, waterfronts and spray decks.
“As Massachusetts will experience some of its most intense heat in the coming days, it’s important for people to make a plan to stay safe," Gov. Maura Healey said in a statement. She urged residents to stay hydrated, limit strenuous activity and check in on people who may be at risk.
Pet owners need to be careful, too. The Animal Rescue League of Boston warns owners stay mindful of pavement temperature on days this hot.
Bridget Willse brings her red fox lab, Finn, to Stoneham's Sheepfold Dog Park, especially on sweltering days. Even though there isn't much shade, she said, it's a better spot for the 2-year-old dog to get some energy out.
"The pavement's a no-go," Willse said. "But at least here there's grass and dirt that keeps the ground cooler."
Still, she'll keep an eye on Finn to make sure he has enough water and watch to see if their visit should be cut short.
For those who want to stay inside but don't have air conditioning at home, there are cooling centers open across the state (find them by dialing 2-1-1). You can see the list of 15 cooling centers in Boston here.
Keeping cool in the AC is a good idea for those who are more vulnerable to heat, including those with health conditions, older people and children. During last summer's heat wave, Boston EMS saw an increase of more than 15% in daily calls, according to the city.
Running all that air conditioning in high heat and humidity, though, can put stress on the electrical grid. Demand for electricity tends to spike in the late afternoons when people come home from work and crank up the air conditioning or turn on other appliances, said Bill Stack of Eversource. "It's the usage that really impacts the system.”
Under this added demand, the transformers, substations and other electrical equipment that enable electricity to get to homes can malfunction. But, Stack added, Eversource prepares all year for heat events like this.
“We make sure that we have the resources in place — which we do — to respond to any public safety issues first,” he said. “And then also to do power restoration.”
National Grid, the other major electrical utility in Massachusetts, also said it has crews throughout the state ready to respond to any heat or storm-related problems.
In general, one or two days of high temperatures and humidity aren’t a huge strain on the system, experts say. It's multiple days of extreme heat in a row that tend to cause the most problems. Last summer, for instance, prolonged heat waves in July and August left tens of thousands of customers in Eastern Massachusetts without power.
To help protect the grid, utilities officials suggest limiting electricity use during peak hours — typically 4 p.m. to 7 p.m. Waiting to do laundry, run the dishwasher or charge appliances until later in the evening or early in the morning can help “shave the peak,” or help eliminate short-term demand spikes.
According to ISO New England, the nonprofit that operates the electrical grid, peak demand is projected to occur Friday afternoon. If the group’s forecasts are accurate, this will be the highest demand day on the grid so far this summer.
“Though we’re expecting to hit a seasonal peak this week, the forecasts are well within what we anticipated coming into the summer,” ISO New England spokesman Matt Kakely said. “We’re not anticipating the need for any emergency actions."
But the group will monitor conditions across the region, he said, and take action if necessary.