By the time late summer hits, most bass are sleepily passing time in the deepest parts of lakes. This is partially due to the heat itself, which forces the fish down into darker, cooler waters. But bass also don't have to work as hard in the summer months because their food supply is so abundant. Unfortunately for anglers, this also means their bait and lures won't be as enticing as they might be at other times of the year. It's still entirely possible to bring in some large bass during the summer, but you'll have to take a specific approach to fishing.
Bass tend to move toward deeper water in response to the heat. As the sun rises in the sky, its rays come down more directly on the water and can penetrate to deeper levels, heating the water. This pushes fish even deeper into the water. Don't be afraid to drop your line toward the deepest parts of the lake, particularly in the evening. Even as the sun goes down and the air cools, bass won't immediately return to the shallower parts of the water. Water retains heat for a long time, so it won't be until the night that shallower waters cool enough for bass to return. Outside of the first few hours of the predawn and dawn light, you're better off dropping your line and trolling in the dark.
Use the Right Lures
To attract bass in their late-summer, deep-water havens, spinnerbaits are commonly used--anywhere from 1/2-oz. to 2 1/2-oz. spinnerbaits are common. These are best utilized with a leisurely retrieve, moving the line slowly near the bottom of the water or even allowing the bait or lure to touch the bottom.
Take Advantage of Bridges
Bridges are constantly shaded and feature varying depths and structures for the bass to hide in. Drop a spinnerbait or crankbait in the water close to structures or pilings closest to the current running under the bridge. Fluorocarbon line works best in this area because it sinks and has refractive qualities almost identical to water, making it nearly invisible.
Look for Vegetation
Lily pads, logs, algae and other aquatic vegetation offer shade for bass, and a consistent food supply tends to come with these locales. Floating frogs are effective in these waters, along with jigs and crankbaits at the edges of the water.