Bass Calendar Periods: Late Summer through Fall Coldwater
September 12, 2019
Largemouth bass behave rather similarly throughout their natural and introduced ranges. The timing and length of prespawn activities, winter movements, and other behaviors, however, vary significantly, depending on latitude and local factors.
In-Fisherman’s 10 Calendar Periods accurately categorize bass behavior by season. Understanding the Calendar Periods will help you fish with consistent success in a variety of lakes, rivers, reservoirs, pits, and ponds. Calendar Periods involve more than water temperature: Often cues also prompt shifts in behavior and location. For example, bass crowd the shallows for a prespawning feed in response to day length, surface activity, and presence of prey, as much as they do to water temperature.
Some important concepts to remember:
- Bass respond to temperature trends more than to a particular degree on a thermometer.
- Temperature can vary significantly from one part of a lake or reservoir to another.
- Bass respond individually to temperature and other environmental factors.
- Size plays a role in a fish's response to the environment.
- Calendar Periods are triggered by a variety of events.
Let’s look at a few timely periods this season…
Water temperature: Warm but cooling
Fish mood: Variable
All good things must end. In late summer, shorter days and cooler waters shift the largemouth’s behavior yet again. In natural lakes, aquatic plants begin to die. Shallow lakes decline first; then, as water turns murkier because of wind and plankton blooms, deep weeds die, too. Bass that have held in shallow areas remain near their declining cover, gradually receding offshore to the remaining clumps of green weeds in deep water—for example, along inside turns.
In reservoirs, bass behavior also shifts. When shad schools move toward shore, largemouth often follow them. Some enter creek areas as water temperatures drop, but they leave again when the water drops into the low 50°F range.
Gradually, as water temperatures drop, the largemouth’s metabolism and appetite wane. Like the spring Postspawn Period, Postsummer is a brief transition between two seasons. Depending on weather and water temperature in a given body of water, fishing may be good or poor.
Water temperature: Upper- to low-50°F range
Fish mood: Inactive
As cold weather rolls in from the North, the surfaces of reservoirs and lakes cool, making their water heavy enough to sink and mix with cooler water in the thermocline below. Wind encourages the mixing, and eventually the thermocline narrows, then disappears. As cooled water from the surface sinks to the bottom, debris bubbles up to the surface, accompanied by hydrogen sulfide and other gases produced by disintegrating plants, releasing a musky or sulfurous smell.
Fishing gets difficult under such conditions, but fortunately, Turnover lasts only about a week on any one lake. Once the lake or reservoir has turned over, the fall Coldwater Period begins.
Water temperature: Cool, declining to cold
Fish mood: Moderately active to inactive
By the time Turnover is complete, a reservoir or lake’s water temperature is usually in the 50°F range. Fish have abandoned their summer behavior and it’s getting cold out there. This is when many anglers choose to end their bass fishing year.
But the Coldwater Period can yield the biggest bass you’ll catch all year, so don’t stow away your gear too quickly. Outstanding catches can be had when you locate groups of bass. Largemouths respond to changes in their habitat by aggregating around the remaining cover in their world. On natural lakes, green weed patches— coontail, pondweed, water lily and milfoil—survive until late in the season and can be found on steep, sloping structure. Before they move onto these slopes, bass that have spent summer buried in shallow weeds first move onto flats with weed clumps in 4 to 10 feet of water. As waters cool further into the mid-40°F range, they move onto or near drop-offs. Once bass move onto drop-offs, they can shift depth without having to move far laterally. Such areas become fall and winter sanctuaries for large populations of bass.
In reservoirs, bass aggregate in creek channels and along the outside edges of weedy flats. These locations make them readily accessible to anglers. If shad school deep offshore, bass stay deep, too.
As long as water temperature remains in the 50°F range, largemouths may continue to feed aggressively, chasing lures. Slow your presentations toward the end of this period: Cold-blooded fish slow down as the water cools. But you can catch bass until the day a lake freezes.