(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
Groundhog Day in American English
US
Feb. 2, when, according to tradition, the groundhog comes out of hibernation: if it sees its shadow, it supposedly returns to its hole for six more weeks of winter weather