The Dog Days of Smallmouth: Reading the River
The Dog Days of Smallmouth: Reading the River
Why Smallmouth Bass Move in Late Summer
Fishing for smallmouth bass during the dog days of summer can feel frustrating—but it doesn’t have to be. When water temperatures rise and oxygen levels drop, smallmouth bass shift their behavior and location. Understanding how temperature, oxygen, food, and cover influence these fish is the key to unlocking consistent success in Iowa rivers. Once you learn how to read these patterns, even the hottest days can produce some of your best fishing of the year.
A Personal Day on the River
It was one of those late summer days where you could chew every breath of humid air. –The bugs were thick– Sweat became commonplace and unavoidable, even in the shade along the riverbank. The water was so warm that a quick dip would hardly offer comfort from the sweltering stale heat. I was fishing for Smallmouth bass and began to wonder if I should have stayed home in the cool retreat of air conditioning. –Silly, I told myself. I am a fisherman and I came out here to enjoy the river and some peace and quiet, I’ll stick it out.
I made cast after cast as I walked along, tossing my spinnerbait into classic smallmouth spots in hopes of tempting a feisty brown bass into biting. One tiny smallie took my lure behind a boulder to lift my spirits but it was hardly enough. My efforts became futile and I began to ponder where the bass had gone. I knew they were in there, but where?
The Breakthrough Moment
Walking farther along, I reached a small stream leading into the river just ahead of a deeper pool. Bending down to pick up a good skipping stone from the streambed my hand was instantly greeted with cold water. A light turned on in my head and I dropped the stone, immediately focusing my attention on the adjacent pool. Instinctively I made a short cast to the outside edge of the pool and without warning my rod doubled over as a hefty bass shot skyward from the water. Upon landing this fish I admired it for a moment, released it and quickly made a second cast. Again, my line went tight and I was battling another respectable smallmouth. This action carried on until I had successfully landed five nice bass from this medium-sized river pool over the course of a half hour.
At this point the sun was setting towards evening and the mosquitoes were trying to drain every ounce of blood they could from me. I walked back to the truck and played the scenario of the evening over in my head. These bass had taken refuge from the hot river water in the cool stream effluent to minimize stress and likely capitalize on abundant food opportunities, not to mention the pool also had a dead tree that was partially submerged protruding from the bank. Oxygen levels were naturally elevated as well since cooler water has a higher oxygen carrying capacity than warmer water. Oxygen—Food—Temperature–Cover. I said these four words over in my head and it dawned on me that these factors alone could quite possibly be the key link to finding late summer smallmouth!
Understanding Late Summer Smallmouth Behavior
It is common knowledge that water temperatures late in the summer become elevated along with sagging oxygen levels that coincide with warmer water. Smallmouth by nature are not considered a warm water species such as a Bluegill or Largemouth bass. Their daily cycles are dictated by many of the same factors that challenge these other species, yet smallmouth are more refined.
Refined in a way that even the slightest environmental changes can drastically affect the mood and habits of these bass.
Temperature becomes the limiting factor in summer river systems. It dictates:
- Where food is located
- Oxygen availability
- Habitat selection
- Daily movement patterns
These all play a vital role for the fisherman in locating bass when the heat of late summer puts a strain on all but the toughest of creatures.
Ideal Temperature Zones & Key River Locations
Smallmouth prefer water around 70°F. Once temperatures rise:
- 85°F+ = stress begins
- 90°F+ = significant stress
- 95°F+ = possible mortality
An adult smallmouth’s preferred temperature range is somewhere in the neighborhood of 70°F. When water temperatures exceed 85°F, adult fish succumb to slight metabolism stress. Beyond 90°F the bass experience stress and beyond 95°F some mortality may occur. With this knowledge you can then assess where key locations in rivers may occur that support cooler, oxygen rich water. These include cool stream effluents, the downstream edge of riffles and habitat structure such as deadfalls and woody debris that experiences or provides shade. Other key areas during warm water include cut banks, deep rocky substrate and current seams adjacent to deeper water.
This forces fish into specific areas such as:
- Cold-water stream inflows
- Downstream riffle edges
- Deep pools and cut banks
- Woody cover and shade
- Current seams near deep water
Daily Summer Movement Patterns
Smallmouth behavior shifts throughout the day:
Morning:
Fish move shallow and feed aggressively in pools and runs.
Midday:
Fish retreat to deeper, cooler water and heavy cover.
Evening:
Activity increases again as light fades and temperatures drop.
This pattern is consistent—but not absolute—depending on river conditions.
Topwater & Reaction Baits (High Activity Periods)
When the bass are aggressively feeding and chasing bait in the morning and evening hours I like to use something that makes a slight commotion and that the bass can pursue. A top choice for this option would be a buzzbait. Buzzbaits cover a lot of water and can be fished slow, fast and through cover. Zara Spooks, Rapala Skitter Props and wakebaits also work extremely well. In the evening time especially, smallies feed actively on terrestrial and emergent aquatic insects at the surface. This is a classic pattern for the fly guys and gals to toss some big bug flies or even a mouse imitation.
Subsurface & Finesse Presentations (Midday Heat)
When the daytime heat drives the bass back into cover and deeper water, a more subtle approach is sometimes required to tempt them into biting. In this case a subsurface, slow moving bait is a classic choice. Drifting a Senko, or other style of soft-plastic stickworm on a bare hook downstream into rip rap and rocky structure is one solid option. Another would be to slow roll a swimjig tipped with a small craw tail through woody structure and rocky areas, and also through pools. Mepps spinners, Shad Raps, spinnerbaits, lipless crankbaits and small swimbaits are also good producers in this fishing pattern.
When fish move deeper, slow down your approach:
- Senkos and stickworms
- Swim jigs with craw trailers
- Spinnerbaits and crankbaits
- Mepps spinners
- Small swimbaits
Work these baits slowly through structure and current seams.
Heavy Cover & Timber Strategy
If the deeper rocky structure isn’t producing, do not count out throwing into woody debris, downed trees and logjams. Just like flipping docks and heavy cover, throw a weighted weedless jig or Texas rigged creature bait into the timber and be ready to pull out an angry bass.
Heavy Cover & Timber Strategy
The bass this time of year will feed on a wide array of forage items to keep pace with their elevated metabolism in warm water. I find that smallmouth are often less picky when it comes to bait selection. Still, try to choose bait colors that closely represent the colors of their natural forage. Shad, crawfish, browns, blacks, whites and even pumpkin colors are top choices. If the bass seem reluctant to hit a larger bait, naturally downsize to a smaller bait and maybe even speed up the presentation.
Turning the Dog Days Into Opportunity
With the dog days of summer upon us, there are bountiful opportunities to catch a big brown bass in many of our Iowa rivers. Pay attention to key river locations and don’t be afraid to try new things. I have often caught my biggest smallmouth of the year during this time by paying attention to specific habitat, light periods and presentations styles. Do some homework on a river near you and have a great summer of smallmouth while it still remains.
What temperature is best for smallmouth bass?
Smallmouth bass prefer water around 70°F. Stress begins above 85°F, making cooler areas critical in summer.
Where do smallmouth go in hot weather?
They move to deeper pools, shaded cover, riffles, and cold-water inflows where oxygen levels are higher.
What is the best time to fish for smallmouth in summer?
Early morning and evening are best, when temperatures drop and bass actively feed.
What lures work best in late summer?
Topwater lures in low light, and slow-moving soft plastics, jigs, and crankbaits during midday.
May 2018
By Nick Johnson
