Yes it is from nearby bodies of water and is really a low flying cloud
I really enjoy when it rains outside!  It makes me want to relax and watch a movie or take a nap! That's interesting! Rain is also responsible for most of our fresh water. Do you find that interesting? Yeah, I have a little garden at my house and I appreciate the rain because it really helps the plant grow faster and bigger! Yes, water exists in all kinds of forms, like glaciers, clouds, fog, and just the humidity in the air. Isn't that neat? I really love the snow as well.  It allows me to snowboard!  I always forget that fog is actually water.
Fog can be considered a type of low-lying cloud and is heavily influenced by nearby bodies of water, topography, and wind conditions.