Boston will be under a heat emergency Thursday through Sunday, Mayor Michelle Wu announced Wednesday.
The heat index, and possibly temperatures themselves, are expected to reach 100 degrees Thursday.
Within the first few hours of daylight, clouds will break for sunshine and this will start the meteoric temperature rise, propelling afternoon high temperatures into the 90s and near 100 degrees for some, according to NBC10 Boston's First Alert forecast. Coupled with a dew point in the 60s representing moderately humid air, heat index values will exceed 100 degrees for a number of communities.
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“We’re working quickly to make sure all of our Boston residents and families are protected during this week’s extremely hot weather,” Wu said in a statement. “I urge everyone to stay cool and safe, and check on your neighbors during the week. I’m thankful for the many City employees who are preparing for this emergency and will be responding to calls for service throughout our neighborhoods.”
Find information on the 16 cooling centers opening at Boston Centers for Youth & Families facilities across the city, as well as the locations of open pools and splashpads, at boston.gov/heat.
The soaring temperatures are also affecting New Hampshire, where the National Weather Service issued a heat advisory for Thursday afternoon and evening.
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It's been two weeks since Boston last declared a heat emergency — that was for the mid-July heat wave, and it required the city to extend its initial heat emergency.
"We get into a very dangerous situation for residents — for workers who work outside, the elderly, people with underlying conditions, out littlest children — so we are keeping cooling centers open in the community," Wu said at the time.
The extended stretch of heat has been impacting Massachusetts, parts of which are under severe drought conditions.
Some cities have required residents to cut back on water use. The heat has even affected the Charles River — in Millennium Park in Boston's West Roxbury neighborhood, the water level has dropped about six feet, revealing many spots that are normally underwater.
