Children's:
Little Bear by Else Holmelund Minarik (illustrated by Maurice Sendak) - This is one of the first books I remember, and I can hear my mother's voice reading to me: It is cold. See the snow. See the snow come down. Little Bear said, "Mother Bear, I am cold. See the snow. I want something to put on."
Snowbound with Betsy by Carolyn Haywood - Several years before I encountered Betsy Ray, I had met this other Betsy, an outgoing girl with pigtails and (later in the series) a little sister named Star. I read every book by Haywood several times and even named my Teddy Bear after a minor character. In this book, a storm cancels school the week before Christmas and some travelers are stranded at Betsy's home.
Winter Cottage by Carol Ryrie Brink - A father and two daughters, down on their luck, appropriate a Wisconsin summer cottage when their car breaks down. The father tries to repair their fortunes by entering contests while teenage Minty yearns for a permanent home. Along with Two are Better Than One, this is my favorite Brink.