Ben Holmes (Affleck) is a 'blurb' writer — responsible for writing the short introductions on the sleeves of hardcover books. On his way to Savannah, Georgia for his wedding with Bridget (Maura Tierney), he's already nervous about flying. His nerves aren't helped when he's seated next to Sarah (Bullock), a free–spirit person who seems to get on his nerves. On takeoff, a bird flies into one of the engines, causing a flameout. Now afraid to fly, he reluctantly agrees to travel with Sarah, who also needs to get to Savannah within a few days.
During the course of their trip, things seem to keep happening to prevent them from getting to their destination — from being on the wrong car of a train, to getting caught in various thunderstorms (thus, the title of the film). However, Ben is impressed by Sarah's easy spirit, and starts to feel a connection with her. As they get closer to their destination, Ben starts to wonder if he's making the right choice in getting married to Bridget, or if he should just let fate take him with Sarah, who has a secret of her own.