Yesterday, I made the rookie mistake of taking my gear directly from the air conditioned room out to the humid balcony air to shoot the sunrise. Of course, the front element of the lens immediately fogged up. After a bit, I took a few shots just to demonstrate the effect. Here's one.
This morning, I put my gear in the bag out on the balcony about an hour and a half before the sun was due to come up. Ideally, I'd use a gallon freezer bag to seal everything from moisture until the gear warmed up, but I don't have any with me. In any case, it worked to a large extent. Here's one without yesterday's fog filter.