Trout are migratory. After spawning, what was once a cozy home would soon be a disaster if they stuck around. The pool could be frozen over and any big trout could be trapped within it. As the chubs and other baitfish migrate for warmer bigger water downstream for the winter, so do trout.
On average, mid-March the fish are making their way back to their summer homes. Lots of challenges on the way too. With the snow melting, water conditions are close to freezing, the water is also turbid with a fast current. The fish must expense large amounts of energy to get back to their former residence.
When the fish finally do arrive for their summering pools, you can guess they have worked up an appetite. I believe mid-March through mid-April is an ideal time to target big brown trout. Just keep in mind water temperature has a lot to do with trout activity, 40 seems to be the magic number. Temperatures under 40 and fish are lethargic and inactive, podded up at the bottoms of deep pools, uninterested in food.
Right now I believe the sun needs to be out long enough to warm the water and turn the fish into feeding. Showing up at dawn to catch that big trout is not the best idea during the catch and release season.