KEVIN VANDAM: The Truths About Water Temperature

Twenty-five years ago, water temperature was viewed as the Holy Grail of bass fishing: it was believed to be the primary factor that influenced bass behavior.

Early bass-fishing literature often cited specific temperatures at which bass would spawn. This implied that if you rode around the lake until you found water that was exactly 68 degrees, every fish in the lake would be in that very spot spawning.

These days, we know that’s not the case. Bass spawn in waters that range anywhere from 55 to 80 degrees, which is a 25-degree range of possible temperatures. But I think water temperature is still a bit overrated in terms of the emphasis anglers put on it for catching fish. I was reminded of this last week when I got out to fish on some of the small lakes around home here in Michigan.

With that, I came up with several other variables that I believe trumps water temperature.

Length of Day

Keep in mind, the water temperature here in Michigan has just barely reached 40 degrees. I’m talking upper 30s to 40 degrees – that’s cold water!

Yet, the bass had already made a move to the bank in the 3- to 5-foot zone. To me, the lengthening of the daylight hours during the spring has far more to do with moving fish to the bank than water temperature does. Yes, water temperature naturally increases with daylight hours too, but when a front slams the water back down to 37 degrees and the fish are still up there in 2 or 3 feet of water – that’s the photoperiod telling them it’s time to get ready to spawn, not the water temperature.

Moon Phase

Last week, I fished through the full moon in April when the water temperature was 40 degrees and I saw fish already up cruising around like they were spawning. Obviously they weren’t on beds, but their behavior was identical to spawning behavior. I’ve seen this before and I’m convinced it’s a sort of false spawn that is triggered by the full moon. It’s almost like a practice courtship even though the water is still 40 degrees.

In my opinion, lunar influences play a larger role in positioning fish than water temperature throughout the year. Lunar cycles not only affect bass themselves, they govern the activities of so much aquatic life: sunfish, shad, crawfish, mayflies, frogs, etc. You can bet wherever this prey is being summoned by a full moon, the bass will be there to take advantage of it, despite the water temperature.   

Current Conditions

Bring in a warm wind on 40-degree water temperatures and bass will get active. The actual water temperature reading on my graph may not budge on a south wind, but the bass sure do!

Also, if the sun beams down into 40-degree water on a cold spring day, any dark object on the bottom becomes a fish magnet. Again, the water temperature itself may not move much, but dark rocks, clumps of dormant vegetation, even rotting leaf debris all create solar heat sinks on the bottom and bass love to get on them.

Reaction Baits Will Work

For a long time, the fables of bass fishing dictated that bass in cold water wouldn’t eat fast-moving lures. The reasoning was that bass metabolism is so low in super cold water they would only eat slow lures that had very little action.

I’m calling “fake news” on this one, too.

I catch plenty of fish on a Red Eye Shad and a jerkbait in 40-degree water. In fact, I experienced a new benchmark last week when I caught bass on a KVD 1.5 squarebill in 38-degree water! That really opened my eyes in terms of just how far you can push a squarebill in cold water.

Water Temperature is Just a Number

Don’t get me wrong, water temperature does play a role in the fish-finding process. But the main thing to be aware of is a change in water temperature with a change in locations.

Is the water in the very back of the creek cooler than the water at the mouths of the creeks? Is the stained water warmer than the clear water? Is the water behind a bridge or inside a harbor or marina warmer than the outside? These differences in water temperature can be a big help in defining a pattern.

Other than that, water temperature is just a number and there is no magic number that is a silver bullet to catching fish.