Carly Hunter is chosen to take the class guinea pig home for the weekend, just in time for Groundhog Day. Tired of winter, she decides to test Piggy's skill for weather-telling.Can Piggy guess the beginning of spring? Will he see his shadow?When the Cul-de-sac Kids hear of Carly's experiment, they join in--and bring their pets. But with all the crew on Blossom Hill Lane there for the party, can trouble be far away?