It's that time of year when the temperature drops and there may even be snow on the ground, but that doesn't mean the fish aren't still biting! Remember, water cools more slowly than the air, so the water may still be at a temperature where the fish are still active - and with trout being cold-water fish, you may find this activity to last all winter!
The first task if you want to fish in the winter is to make sure the season is still open. In Pennsylvania, trout season closes on September 3 - except in "approved trout waters," so if I want to fish in the cold, I need to make sure I am headed to one of the streams on the PA Fish and Boat Commission's list. Fortunately, the Yellow Breeches Creek is nearby.
The next concern is staying warm. You will get cold fast standing in the water, so make sure you bundle up. This is where a pair of neoprene waders (which insulate better than hip boots or rubber waders) comes in handy. You'll also want to wear something insulating underneath them, so long underwear or sweatpants might actually be more comfortable than jeans or khakis.
If you really want to get fancy a base layer like WhitewaterS3 Expedition Baselayers (pants and shirt) is really nice to have. A base layer will wick away moisture if you find yourself sweating and insulate your body heat when your standing still.
You'll of course want a warm winter jacket - or better yet, several layers that you can shed if the need arises. Your fishing vest should be able to fit over top of all these layers.
The trickiest thing to keep warm is your hands. Waterproof gloves are a must. I really like Glacier Glove's Fleece-Lined Neoprene Gloves. They are built to have a tactile feel but with thumb and finger slits, you can still get some extra dexterity by temporarily poking your finger or thump through the slits to tie a lure or untangle your line. These slits only minorly affect the gloves water proofing and you'll get just a minimal amount of water in them should you have to reach in the water.
Finally, you'll of course want a warm hat that will keep your ears warm. You can do this with an earflap hat or an regular beanie. The advantage of the earflap hat is that you won't have to adjust it often out on the stream, but you will look cooler with a beanie.
Just because winter's here, doesn't mean you can't catch trout. Just find legal waters and bundle up and you can have a great time catching fish at a local stream.