Stormy, Misty's Foal by Marguerite Henry (Paperback)

Misty is a Chincoteague pony mare who is close to foaling and the Beebe family is anxious about it. Paul and Maureen check on her every day before and after school at almost every possible time. Unfortunately, a terrible storm system arrives first, setting up over Chincoteague with floods, hurricane winds, ice, and snow.