This proverb is about Imbolc or St. Brigid's Day, a Gaelic festival which marks the beginning of Spring on February 1st. In Scotland, St. Brigid is the patroness of serpents. Her festival is related to weather divination. The practice was to see if snakes or badgers came out of their holes on this day as a prognostication of whether or not the winter will last much longer. This may also be the origin of Groundhog Day.