Greetings from PA, funforfree!! This is a great place for information and will have your chops up to par in no time.
You can technically fly fish all year round, but around here I can't fish now on "Trout Approved Waters" do to the season's opening day in 2 weeks. But on other waters I can. I know around here the best flys are scuds and worms and possibly some stoneflys. Wolly bugger is also a good year round pattern.