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It may be broiling on land, but the water north of Boston Harbor is still freezing

Matt Noyes at NECN confirms what North Shore and Cape Ann ocean swimmers already know: Brrr.

The cooling ocean water really became noticeable after the first week of July as two phenomena occurred back-to-back to send water temperatures spiraling. First, a feed of colder water sliding south down the Maine coast surged along the Cape Ann shoreline and entered Boston Harbor from the north. Interestingly, ocean currents helped the water miles offshore recover fairly quickly over the last two weeks, but closer to shore, not only was a cooler pocket of water trapped, but a new phenomenon took hold: upwelling. Upwelling is a common occurrence for any coastal community near the open ocean – when the wind blows from off the land, usually a northwest, west or southwest wind in New England, that wind pushes the skim of relatively shallow, milder ocean water out to sea. The void left behind near the shoreline has to be replaced, so new water rises up from deeper, colder ocean levels to replace it, causing a drop in water temperature near the shoreline.

Confirmation of his confirmation comes from Hkergrrl, who went for a swim yesterday:

Just got back from nahant and can confirm that it is still wicked cold in the water... Pleasant at first and then completely numbing

Free tagging: 


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Narragansett area beaches are around 70 degrees. I will be at Scarborough tomorrow if you need me…

Voting closed 15

Never ventured beyond the sand... "this is a nice spot to swim, er, shovel"

Voting closed 11

75 degrees.

There's a reason why I never went to the Cape in summer in 19 years of living in Boston.

Voting closed 12

I have always found that Ocean temps from 60-65 are "cold", but bearable and refreshing on a hot day. Sometimes swimming in temps 60-65 feel really nice on the body.

Anything under 60 is unbearable though. 65-70 is nice and over 70 is amazing.

Voting closed 20

The National Center For Cold Water Safety categorizes 60-70F as Dangerous and 50-60F as Very Dangerous/Immediately Life-threatening. Apparently 50-60F is the critical range for cold water shock, which causes hyperventilation and loss of breathing control. It's cold shock that usually kills people, rather than hypothermia, which takes half an hour or so to set in.


I'm a little skeptical of these categories, particularly calling 69-degree water "dangerous", but this source seems less tainted with misinformation than most.

Voting closed 9

This is the qualifier missing from the provided stats.

50-60 after falling off a boat in March is completely different from swimming at the beach for extended periods during a heat wave.

I've given myself mild hypothermia while bodysurfing in early May in perfect surf conditions well under 55 degrees.

Air temp was fine but I was definitely in "cold water shock," shaking and cross-eyed when I got out.

In no real danger though unless I hit my head on the sandbar and got knocked out.

Voting closed 10

You mean AHHHH!

Voting closed 5

… the other day to stave off heat exhaustion. Not quite the delicious tingle you get off Cape Ann but close enough.

Anything above 65 is used bath water and not for me.

But nothing no nothing beats a swim in the sea on a sunny day in late December! Ahhhhhhh!

Voting closed 9