Sam Baldwin, a Chicago architect, loses his wife Maggie to cancer. He and his young son Jonah start anew in Seattle, Washington, but Sam continues to grieve.
A year and a half later, on Christmas Eve 1992, Jonah—who wants his father to find a new wife—calls in to a radio talk show. Jonah persuades Sam to go on the air to talk about how much he misses Maggie. Hundreds of women from around the country hear the program and touched by the story, write to Sam.
One of the listeners is Annie Reed, a Baltimore Sun reporter. She is engaged to Walter but feels there is something missing from their relationship. After watching the film An Affair to Remember, Annie impulsively writes a letter suggesting that Sam meet her on top of the Empire State Building on Valentine's Day. She does not intend to mail it, but her friend and editor Becky does it for her and agrees to send Annie to Seattle to "look into doing a story on those radio shows".
Sam begins dating a co-worker, Victoria, whom Jonah dislikes. Jonah, a baseball fan, reads Annie's letter and likes that it mentions the Baltimore Orioles, but he fails to convince his father to go to New York to meet Annie. On the advice of his friend Jessica, Jonah replies to Annie, agreeing to the New York meeting.