The cause is something called upwelling. Steady southwest winds pushed the warm surface water away from shore, and to replace it, frigid water from deep in the lake rose up to take its place. Lake Superior is cold and deep, so there's always an icy reserve waiting just below the surface. Give the wind the right angle and it comes straight up to the top.... Upwelling usually reverses once the winds shift, so the warmth will likely creep back in a few days. But this is a classic reminder of what makes Superior, Superior.
July 14, 2026
Upwelling.
The water around the Apostle Islands was 70°F yesterday afternoon and 46°F this morning — a 24° drop, so it says on the Apostle Islands page at Facebook.
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35 comments:
Cool.
We experienced that phenomenon on a family trip to the outer banks about 15 years ago. There was a heat wave with the temperatures in the high 90's all week. The wind was blowing hard offshore from the west, instead of the usual southwesterly breeze. The dunes blocked the breeze on the beach. It was really, really hot on the beach, and the water temperature was 52 degrees. Everyone was huddled in a narrow strip right along the surf line. Bizarre. Lot's of beer was consumed to alleviate the effects.
"The big lake they call Gitche Gumee" ... I need to check out Superior up close one of these days. I'm most familiar with Lake Michigan as I lived in Evanston, IL for a few years.
I thought that that was called a seiche, at least that’s what the old walleye fishermen call it, but standards of journalism are not what they once were.
The thermocline bounces around, which affects the fishing, some lakes are kind of like lava lamps if you are aware of what is going on.
Brings to mind the West Coast. The entire Pacific waterfront is fed by the cold, deep Gulf of Alaska. The only 70 degree pockets are in protected coves and bays. O'Neil Surf Shop derives from surfers struggling to stay in that frigid water -- they invented wetsuits.
In the California coastal cities north of Santa Barbara you can spot the tourists per their shorts and the emergency local sweatshirts they bought to keep warm, including "Carmel by the Sea," "Monterey," "Santa Cruz," San Francisco," etc.
The walleye fishermen cared because a seemingly still lake will often have a “wind tide” so they look at the weeds to judge its direction and you can maybe infer where in the structure the fish are feeding.
Salmon and lake trout fishermen care because water is densest at 39 degrees, which is the temperature that their targets like, and as the summer progresses, this gets deeper by the week. Right after ice out, you can catch a salmon in four feet of water from shore, by August, they are 90 ft down.
Years ago, and I mean lots of year ago, we used to snorkel near Marquette in late July and August. The first three feet might be 65-70 degrees. The next 10 feet would be 10 degrees colder and below that it would shock you into immediately surfacing.
I swam in Lake Superior in my youth. We were up at the Log Slide Overlook, which are ~300 foot high sand dunes that descend down to the lake shore. We worked up quite a sweat climbing down to the lake, and took the plunge. I don't know what the water temperature was, but it wasn't the coldest I'd ever swum in (that was in the Atlantic at a Maine beach, around 50 degrees). This was probably more like 60. Then we had to climb back up the dunes, which took a couple of hours as I recall. Filed under "crazy things we did as kids."
There's a pretty good book by Leif Enger called "I Cheerfully Refuse" that takes place on and all around Lake Superior. Enger writes beautifully, and even though I don't think this is his best book, it's still a very good read. It's an almost Odyssey-like story of a man searching for his wife while being pursued, going around the lake, to islands in the lake, to various (fictional) towns along the lakeshore. He paints a very real picture of Lake Superior as a being in and of itself.
You can probably purchase the book through the Althouse portal, thereby helping two people I enjoy reading.
"Jaq said...
I thought that that was called a seiche, at least that’s what the old walleye fishermen call it, but standards of journalism are not what they once were."
Seiches effect water levels, not temperature. Lake Erie, being very shallow, as them. If fact, they had one last year.
As the warm water presses against one side of the lake,it forces down the thermocline, and the cold water pops up on the other side of the lake, to fill the space left by the warm water that has been blown down wind. It’s not an either/or thing. Of course the behavior varies a lot from lake to lake.
Grok explains the differences between a seiche and an upwelling:
• Motion: Seiche = horizontal oscillation/slosh (standing wave). Upwelling = vertical ascent of deep water.
• Primary driver: Seiche often from wind/pressure shifts causing rebound. Upwelling from sustained winds displacing surface water offshore.
• Scale and impact: Seiches affect water levels and currents in basins (sometimes dramatically but temporarily). Upwelling sustains biological productivity over larger areas and longer periods.
• Overlap/relation: Both can involve winds in large lakes (e.g., Great Lakes), and a seiche might indirectly influence layering that affects upwelling-like processes, but they are separate.
In short, a seiche is about water rocking in place, while upwelling is about deep water rising to “feed” the surface.”
I suspect Althouse and Meade have been traveling, again.
"Coastal upwelling" is a big thing in marine biology.
One of the coldest summer days I ever spent was a July afternoon at the Superior shore in Duluth.
Maybe it’s because the lake I know best has variations in the thermocline of 40 to 60 meters, 60 is unusual, and while the cause of an upwelling is likely a seiche, I will concede that they are not the same thing, but I do think that an upwelling is unlikely to occur without a seiche. What other external forcing is there, unless this is a regular periodic event.
* The surface of Lake Champlain undergoes basin‐wide oscillations with amplitudes of a few centimeters and a period of four hours. The summer thermocline undergoes basin‐wide vertical oscillations of 20 to 40 m with a period about four days.*
https://www.science-frontiers.com/sf121/index.htm
Gordon Lightfoot.
The famous saying "Lake Superior never gives up her dead" is rooted in scientific reality: the lake's frigid, oxygen-starved depths halt the natural decomposition process, preventing sunken bodies from bloating with gas and resurfacing. Instead of floating, victims remain permanently submerged in a state of cold stasis.
My balls shriveled just reading this. I’m sticking Lake Inferior
This is great, all the people who swim in Superior will be full of serotonin now. Depression will be cured.
You don't need a thermometer to tell when you're close to an upwelling. Your nose will inform you.
There was up-welling at the creation
``When there was as yet no shrub of the field upon earth, and as yet no grasses of the field had sprouted, because Yahweh had not sent rain upon the earth, and there was no man to till the soil, but a flow welled up from the ground and watered the whole surface of the earth, then Yahweh molded Adam from the earth's dust (adamah), and blew into the nostrils the breath of life, and Adam became a living being.''
If you're up that way, you could catch the Jayhawks at the Big Top Chautauqua on Friday night. Decent enough (Minneapolis based) band at a really enjoyable venue.
There is a comedy group in Duluth, MN, called Colder By the Lake.
You”re making me think about one of the most interesting mysteries I’ve read — “A Superior Death” by Nevada Barr. Barr wrote a 19-book series set in various national parks and centered on National Park ranger Anna Pigeon. Pigeon is a law enforcement ranger, with powers of arrest and allowed to carry a firearm. (You can get the series through the Althouse Amazon portal. The series begins with “Track of the Cat,” set in Texas. “A Superior Death” has the most challenging crime scene ever — inside a sunken ship hundreds of feet below the surface of Lake Superior, within the boundaries of Isle Royale National Park.
The Anna Pigeon series petered out about a decade ago, and I miss them.
Big Mike, do any of the national park murder mysteries cover the alleged small piece of (I think) Yellowstone where no court has jurisdiction? CC, JSM
@john mosby, I don’t recollect any.
@john mosby "Free Fire" by C.J.Box
@nohn mosby, I did some research — none of the 19 has Yellowstone as its setting.
25 book series about sometimes park ranger
Strong consistent south west winds cause upwelling along our shore of Chesapeake Bay. Although the deeper water brought to the surface is a little cooler, the main issue is that the deep water often has low or no oxygen causing fish and crabs to crowd into the waters edge. In the good old days this was called a crab jubilee. These days they mostly falsely blame a red tide.
The officer involved in the fatal shooting in Maine was hired by ICE this year from the Department of Veterans Affairs Police, according to the senior official. The officer has worked in federal law enforcement since 2017, the official said. Neither detail has been previously reported. The shooter in Maine has not been publicly identified; neither has the shooter in Houston, where the earlier fatal ICE shooting occurred.
So with all his prior federal policing experience, the unnamed ICE agent obviously bribed to join ICE, allow his childish fear and stupidity to suddenly "well up" and cause him to draw his gun and shoot another man in cold blood? And why is the public being influenced to "well up" in anger over these continued killings of the innocent?
Thanks, gadfly, for that upwelling of self-righteousness. To condense your post, you believe that the constables blundered, and that we must therefor be dispossessed of our nation's values and traditions.
Placed hold for TX book title
“To condense your post, you believe that the constables blundered, and that we must therefor be dispossessed of our nation's values and traditions.”
No, these ICE agents aren’t constables and they are dispossessing us of our nation’s values and traditions.
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