You know that weekend in fall when everything should be perfect? Cool morning, no bugs, the trees doing their thing along the shore. And then you fish your best spots for five hours and get exactly nothing. The water looks a little murky, maybe smells a bit off, and the fish you were catching last week seem to have packed up and left town.
There’s a good chance it wasn’t you. It might be fall turnover.
What turnover actually is
All summer, a lot of lakes sit in layers. The sun warms the top, and that warm water floats on a big pool of colder, heavier water underneath. In between there’s a narrow band where the temperature drops fast. Anglers call it the thermocline, but you can just think of it as the floor between the two layers.
Those layers don’t mix much. The bottom layer gets cut off from the air, so over the summer it slowly runs low on oxygen. That’s why in August so many fish hang out above that floor, where they can breathe.
Then fall shows up. Cold nights chill the surface, and cold water is heavier than warm water, so the top layer starts to sink. Wind helps stir things up. Bit by bit the top and bottom get closer in temperature, and at some point the floor between them just gives way. The whole lake mixes from top to bottom. That’s turnover.
It sounds dramatic, and for the fish it kind of is. The old stale water from the bottom gets churned up, oxygen levels get shuffled around, and the cozy summer spots stop making sense. Fish scatter while things settle down. For a few days, sometimes a couple of weeks, the bite can be tough.
How to tell your lake is turning over
There’s no official announcement, sadly. But the lake drops hints:
- The surface temperature has fallen to somewhere around the low to mid 50s °F (about 10-13 °C), and it keeps falling.
- The water looks cloudier than usual, sometimes a bit brown or green.
- You notice foam, floating gunk or bits of weed drifting in open water.
- There’s a faint rotten-egg or swampy smell, especially on calm mornings.
- If you have a fish finder, the thermocline line you saw all summer is gone, and fish show up scattered at all kinds of depths.
One more thing that surprises people: lakes don’t all turn over on the same day. Shallow lakes and ponds often mix first, and some barely layer up in summer at all. Big, deep lakes usually turn later. Two lakes ten miles apart can be a couple of weeks out of step.
How to fish through it
The good news is that turnover doesn’t last forever, and you can still catch fish while it’s happening. Here’s what tends to help.
Switch lakes
This is the easiest trick there is. If your lake looks like pea soup, try a different one nearby, ideally one that’s much shallower (it may have already turned and settled) or much deeper (it may not have turned yet). Rivers and streams don’t layer up like lakes do, so they’re a great backup during these weeks.
Fish shallow and stay mobile
During the mix, fish don’t have a reason to stick to one depth, and plenty of them roam the shallows, where the water warms up a touch on a sunny afternoon. Cover water instead of parking on one spot. Fish a point, a weed edge or a rocky bank for twenty minutes, and if nothing happens, move on.
Slow down
Fish in water that just got flipped around are often a little off their game. Smaller baits and slower presentations usually beat big, fast ones. A jig (basically a hook with a weight molded onto it) hopped slowly along the bottom is hard to beat. A jerkbait with long pauses between twitches works well too, and it’s often the pause that gets the bite.
Walleye after dark
Walleye see well in low light and often move up shallow in the evening, especially around rocky points and gravel flats. When daytime fishing is slow during turnover, the hour around sunset and the first part of the night can still be good. A slow jig or a minnow-shaped lure over rocks is a classic for a reason.
Bass on the bait
Bass in fall are thinking about one thing: eating before winter. Find the schools of small baitfish and you’ll usually find the bass nearby. Watch for birds diving or little fish flicking at the surface. A lipless crankbait or a swimbait that looks like those baitfish is a good place to start.
The bite comes back
Here’s the part worth remembering on a slow day. Once the lake finishes mixing and the water clears up, there’s fresh oxygen everywhere, from the surface to the bottom. Fish can live comfortably at any depth again, and with winter coming, they’re hungry. A lot of anglers think the weeks after turnover are some of the best fishing of the whole year.
So if the lake goes quiet on you in October, don’t hang up the rods. Give it a week or two, keep checking, and be there when it wakes up.
Stay warm out there
Fall water gets cold fast, and cold water is a lot more dangerous to fall into than it looks. Wear your life jacket, dress in layers, and let someone know where you’re going. The U.S. Coast Guard and Canada’s Lifesaving Society have good, plain advice on cold-water safety, and our disclaimer is a reminder that you’re the one who decides what’s safe on your water.
Something to try next time
Next trip, jot down the water temperature and what the water looks like, along with what you catch (or don’t). It feels pointless on the bad days, but after a season or two you’ll start seeing your lake’s own pattern: roughly when it turns, how long it stays grumpy, and when the bite comes back. If you use Vobbl, a quick note on the catch does the job, and the weather gets saved with it anyway.
Tight lines!