when going in winter months i suggest a variety.
some pants, some shorts, short sleeves, no long sleeves, a couple hoodies or light jackets for early in the morning and late in the evening, swimsuit....
and i usually forgo the heavy winter coat even though its cold where i live but there have been times that i wished i had a heavy coat at disney so it is a good idea to have it just in case.
the weather can change while you are there so even though it says mid 60's/low 70's as of now that could very well end up changing to highs in the low 80's or highs in the low 40's in a snap so its best to be prepared.