Look for Shade
Learning what bass consider shade from the midday sun is the key. When the sun is directly overhead, bass will seek any structure or cover that provides shade. If none is available, they will move to the deepest water possible. This is where having a depth map of a lake or river can help.
Look for weed cover in the shallows. When weeds are present the bass will be under them. If there are no weeds, docks and similar structures will draw bass in sunny conditions. If the body of water has none of these features, look for deep drop-offs on the lake bottom and concentrate efforts there.
If you take the time to locate all of these elements, you can save time and reduce fruitless casts.
Head for the rivers during heat waves. There is more oxygenated water in rivers and streams than in ponds and lakes, since the water is moving. Shallow rivers shaded by trees are ideal places to find smallmouth bass. Largemouth bass will be found in shady spots where the current is moving slowly. If the river is shallow enough along the edges, the best strategy is to wade in wearing old shorts and sneakers. This way you can avoid shoreline vegetation while casting and better target spots that hold bass. A good fishing vest that can hold bait, hooks, weights, and other tackle is a necessity for this type of midday bass fishing.
Slow Your Retrievals
Bass are not prone to quickly chasing potential meals in the heat of the day. You need to make it easy for the bait to be caught or ambushed by the bass. Drop jigs and Texas rigged plastic worms into heavy cover that offers shade. Fish the lures slowly and give the bass a chance to see them.
Downsizing baits also is a good idea. In rivers, a simple night crawler rigged on a No. 4 snelled hook behind a pair of split shots will catch largemouths and smallmouths. Casting two-tailed plastic grubs downstream and reeling them in very slowly can get a hit. Smallmouth will offer at such presentations even at midday.