Seatrout, found up and down the east coast of the U.S. and along the entire Gulf of Mexico coast, are not really migratory fish. They don't move great distances with seasonal changes, and they can be caught year round. The trick to catching them is to know here they will be in any given weather situation.
Basically a warm water fish, seatrout like comfort. Just as you and I seek air conditioning when it's hot, and a heater when it's cold, these snaggle toothed beauties look for a water temperature that keeps them comfortable. In cold water, they will make short migrations to areas that have a relatively stable temperature. In the winter, that generally means the deepest water in the area.
The myriad creeks and rivers that penetrate the shoreline estuaries from Virginia all the way around to Texas all have some things in common. They all twist and turn, yielding to tidal flows, and they all provide excellent deep water temperature shelter fro not only seatrout, but a variety of other fish as well.
As the tide moves in and out of the creeks and rivers, it makes an impression, literally, in each twist and bend. The flow of the water carves a natural hole on every outside bend. The sharper the bend, the deeper the hole. At low tide many creeks are not navigable, but the holes on the bends will still hold up to ten feet of water. Deep water cools and warms slower than surface water, and that temperature stability will keep the fish in the holes.
So get the out the coastal charts and find the holes in the creeks. Not every hole will have fish every day, but you will find some that consistently have more fish than others. The way to find out is to fish them!
Try a finder float rig with live shrimp, setting the depth for the float to be about three feet off the bottom. The finder float is a long slender float, from six to fourteen inches long and up to an inch in diameter. Line is passed through the middle of the float, where a bead and float stop knot (see How to Tie a Float Stop) set the desired depth. The float size will vary with the weight required to keep line to the bait vertical in current. The more the current, the more weight is required, and accordingly, the larger the float. The slender float design makes it easy for the fish to take the float under.
Once I anchor upcurrent from the hole I plan to fish, I put a bait in the water next to the boat. Then I allow the float and bait to drift with the current through the hole. If trout are there, they will bite. And if one is there, there will be many there. This is the time that the largest trout can be caught. "Gators" of ten pounds or more are not uncommon from cold water holes.
It is entirely possible to catch the entire school of seatrout from one hole. Consequently several states have imposed a closed season during colder months. Florida, as an example, closes seatrout during November and December in the South Region and all of February in the Northeast and Northwest Regions of the state. This is partially because they generally are the coldest months of the year.
So, if you venture out to find a cold water seatrout hole, remember your catch and release conservation rules. Have fun and catch them all, but release them properly.