The book is aptly titled One Day in December because December is the month that opens and closes the novel. It is one day in December when Laurie and Jack meet eyes on the bus, and one day in December when they finally reunite as lovers. The holiday season that starts in December is an important motif in the novel. Laurie’s experience with Christmas is usually that of stress, and with each approaching New Year’s Eve she is reminded of her shortcomings. Even when the majority of important events in Laurie or Jack’s life occurs in the summer or autumn months, the New Year always marks the start of a new cycle, while Christmas marks the end of that cycle.

The metaphor of swimming is used throughout the novel by both Jack and Laurie as a way of describing growing through the trials and tribulations of life. When Laurie and Jack are in their early twenties, they describe swimming against the current, a symbolic way of saying their lives are stressful and that they’re not getting where they need to be. Later in the novel, when they have their lives under more control, they feel as though they are treading water—they’re not moving forward, but they’re also not being pushed backward.