All year long is great for flounder. A lot of people focus on the runs, but you can catch them all summer. They will stack up in the back bays and shallows. Find moving water close to grass or coming out of the marsh, they are there. Since they are ambush predators, they will lay in wait for something to float or swim by. Its a lot like Crappie fishing. Use a jig under a cork or free floating plastic bait. If they are slow, add a pinch of shrimp to the hook or spray on some scent.