The trout are biting all over the coastal marsh, the reds are active inside the bayous and ponds, and sometimes it's hard to make yourself shut it down and head back in when the action is so productively hot and heavy. But the word "hot" has a significant meaning here.
Out on the Louisiana coastal waterways, it's easy in all the excitement of fish catching to succumb to overheating, heat exhaustion, and heat stoke without any significant warning. You start sweating heavily, then you stop sweating, then you get weak and dizzy and nauseous, then you collapse. This affliction is common, especially for fishermen, shrimpers, and crabbers who find themselves out in the sun for a long time.
So do this: wear the proper clothes (shirt and pants made of cotton that allows the skin to breath and the sweat to evaporated thus providing natural heat dissipation), use a wide-brimmed hat to ward off direct rays of the sun, fish under a structure (bridge or petroleum platform) to get out of the sun when possible, don't fish hungry (even a half sandwich will provide necessary body-cooling energy; and--most importantly!)--drink, drink, and drink some more. Drinking, even when you don't feel thirsty, is what keeps you hydrated and wards off heat related symptoms.
Bring along plenty of water and power drinks (like Gatorade) to replenish your electrolytes and keep them in the cooler "ice cold." Many of the sporting goods stores also stock baseball-style caps with thermal packets built in that you stash in the ice chest and put on while you're fishing. It cold temperature on the top of your head helps keep your core temperature in check. Some sporting goods stores also handle thermal neckerchiefs that work the same way. They're really inexpensive, so pick up a few and use them.
Finally, visit your favorite drug store and buy a small spritzer bottle, will it with cold water, and spray yourself throughout the day to induce evaporation. You can also stop in at your pharmacy and buy the ingredients you'll need to make a batch of "Florida water" (the druggist can tell you how to do it--if he can't ask your local high school football coach).
Whatever it takes, stay cool and hydrated.