King tides bring flooding — and a glimpse of the future — to downtown Boston

Here's what it looked like.

Ted Rye, of Needham, carries his shoes as he walks through the water at Long Wharf during the second day of three king tides in Boston.

Boston Harbor inundated the city’s waterfront Tuesday for the second time this week. But it wasn’t because of any rain or storm surge.

Rather, it was the semiannual return of the king tides.

The unusually high tides occur once or twice a year when the orbits of the sun, moon, and Earth are aligned and result in a sea level rise up to two feet higher than average high tides. This week, that meant minor flooding in downtown Boston, particularly at Long Wharf, where onlookers took the opportunity to splash through the few inches of ocean water that had overflowed onto the historic pier.


People take in the scene at Long Wharf during the second day of three day “king tides” in Boston Harbor.

According to the National Weather Service, this week’s tides in Boston peaked at over 13 feet and 2.5 inches around 11:45 a.m. on Monday and at more than 12 feet and 4 inches shortly after 12:30 p.m. on Tuesday. In some places Monday, the flooding was reportedly up to a foot on Long Wharf.

The flooding also provided a glimpse of how climate change could affect Boston in the coming decades, even if the astronomical tides are not themselves related to the warming planet.


“King tides preview how sea level rise will affect coastal places,” reads the website of the Environmental Protection Agency. “As time goes by, the water level reached now during a king tide will be the water level reached at high tide on an average day.”

Sen. Ed Markey, a longtime environmental advocate, tweeted that the flooding seen Tuesday afternoon “will soon become an everyday norm.”

A father who did not wish to give his name holds his 27-month-old son as they walk through the water Tuesday on Long Wharf.

Climate change experts generally agree, if changes aren’t made first. The City of Boston currently projects high tides to increase by 21 inches by the 2050s and by three feet by the 2070s over its current levels. And that doesn’t factor in the effects of wind and storms, which can add several additional feet in surge.


“Sea level rise is making the tides higher because they’re starting from a higher base,” Curt Spalding, the EPA’s regional administrator for New England at the time, told Boston.com in 2016, adding that what was more troubling was that the king tides often coincide with the fall storm season.

“If you stack a tropical storm, a tidal surge, on top of a king tide like event, which is really just the tides we have in October, we’re looking at a very significant risk,” Spalding said.


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