Keep it in your bag, sealed shut. If you have a balcony or a safe place to stick it while you get ready in the am (even the bathroom works sometimes), put the bag out there until you're ready to walk out the door. I also collect those little packets that come in medicine bottles, electronic boxes and toss a few in my bag to (wishful thinking ??) absorb any moisture in the bag.
And I would not put any chemicals like Fog-X or Rain-X on your lens! I see what it does to my windshield and to have to deal with the smearing on my lens-no way!!! On that note, be sure to bring along something to clean your lens with just in case. I have a Lenspen and microfiber cloth in my bag.