(in the US and Canada) February 2nd, when, according to tradition, the groundhog emerges from hibernation; if it sees its shadow, it returns to its burrow for six weeks as a sunny day indicates a late spring, while a cloudy day would mean an early spring
2.
a situation in which events are or appear to be continually repeated
Word origin
C20: sense 2 from the film Groundhog Day (1993), in which the lead character experiences the same day repeatedly