The Secret Window by Betty Ren Wright

Meg's dreams seem to predict the future-but can she make a better future for herself? "Filled with sensitivity and warmth" (Children's Book Review Service).
"It was crazy to have dreams that came true. If you talked about them, it'd upset the people you loved and make them angry. Meg had learned something bad about herself, an ugly secret." And so she decided to keep the dreams to herself, writing them down in a special notebook. Sometimes her dreams were pleasant, but other times they were disturbing-especially the one about the cave with the blue light.

When Meg's worst dreams begin to come true, she's convinced they bring bad luck. Why else would her father move out to "find himself" or her best friend desert her for a rowdy crowd of older kids? Meg's grandmother and a wonderful new neighbor finally help her realize that her "secret window" into the future can bring good luck, if understood properly.