Tuesday June 04, 2013 | 07:53 AM
Posted by Harold Johnson

And suddenly, summer arrived! A chill and dismal May broke this past weekend into sweltering June, and Mainers hit the beaches for a break. But when their toes touched the water, many were in for a shock. The ocean temperature along most of Maine’s coast has barely breached 50° F (12° C)!

(Source: NOAA’s “Sea Surface Temperature Images” page -- available to anyone, updated twice a week)

In fact, even by the end of a broiling summer, the waters of Saco Bay (typically Maine’s warmest*) barely reach 60°.


First, our surface currents come from the northeast. Maine’s coast lies in the path of the Labrador Current -- which gets its source from the glaciers of Greenland. The current hugs the coast of North America, bringing Arctic-chilled surface water with it.

It’s this current that brings so much Canadian debris to my southern-Maine shores, like:

(lobster claw bands lost overboard by a Canadian lobster boat)


(Canadian lobster trap tag)


(Scrap of “Javex” bleach bottle - Canadian brand)

But the Labrador Current alone doesn’t fully explain why our waters are so cold. Warm Gulf Stream currents are always flowing northward from the tropics, reaching as far as Cape Cod. One would think they would mix & swirl, and have some effect on our waters.

But we largely miss out. Because of the really special nature of the Gulf of Maine.


We live next to a sea-within-a-sea. The Gulf of Maine is a group of deep basins set within a ring of shallow banks. There are few places where the open Atlantic can freely mix with Maine’s waters. Hugging the coast, the chilled Labrador can get in. Not so for the warmer southern waters -- which are, in any case, already getting pulled to the east and away from North America by the time they reach New England.

So, this summer bring your sunblock, your frisbees, your blankets & umbrellas. But if you’re planning on swimming, bring your hardiness too. No matter what time of year, in Maine you’re going to need it!


* Saco Bay is fairly shallow, so it’s easier for the sun to warm its waters. Also, the Saco River is constantly emptying its sun-baked waters into the bay. As a result, Saco Bay can be several degrees warmer than beaches just a short drive north or south.

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About the Author

Visiting a Maine beach in March 2010, Harold Johnson was shocked by the ocean-borne debris left by recent storms. He grabbed a garbage bag and a camera, and hasn’t looked back.

Since then he has spent most of his free time studying marine pollution, coastal ecosystems, and the mysteries and science of ocean and shore.

Copyeditor and writer by trade, historian and archaeologist at heart, Johnson’s philosophy is simple: Dig below the surface, travel the currents, make the connections, learn. Then share what you learn. He lives in Saco with his wife and young daughter. Follow on Twitter @FlotsamDiaries.

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