SOLVED. A girl and her mom moved to a new house by the ocean, and when playing in the mist, she made a friend. He (?) was only there in the mist [s]

[Brandie]

This one is a long shot, but I had such good luck with the other one I posted that I thought I'd try...
I read this when I was maybe 10, so it is from the early 80's, if not older. All I remember is that a girl and her mom moved to a new house by the ocean, and when playing in the mist, she made a friend. He (?) was only there in the mist, and it turned out that the entire village she'd been visiting was no longer there...
Any help would be so greatly appreciated!

[Recynd]

Urgh...I read that book!! Another one that is more dreamlike in my memory than substantive...thanks a LOT (*wink*)!

If I can figure out the book, I'll post the name.

[Alexandra]

I haven't read this book, so this is a blind guess, Fog Magic by Julia L. Sauer?

[Brandie]

It is, actually--I had forgotten to change the post to solved, though. Thanks!