It's a very humid day here just outside of Boston. I sat down to practice (I'm just learning to play) and I found my fingers are literally sticking to the keys. Eeeewwww!!
Is this common, and is there anything I can do besides wait til the humidity disappears? (I have a new Yamaha YPG625)

Yes. Keep your keyboard free of oil and sweat with a moistened soft damp cloth and water. Also make sure your hands are clean and dry.

I have the same problem because I don't like to run the A/C but don't want the piano to prematurely drift out of tune just to save a few bucks on my electric bill.

Playing a piano in a humid environment is like playing pool: There's a reason why they put chalk on the cue and on their hands.

Well, I'm glad it's not just me. Thanks for the suggestion. It's drier here today, and much easier on the keys, but I'll be looking for that damp cloth again soon, I'm sure!