We all know the saying: If the groundhog sees his shadow on Groundhog Day, there’ll be six more weeks of winter. If not, then it’s an early spring. In the United States, it’s a tradition that dates back almost two centuries. But it’s based on far older traditions, which were based in part on the seasons.

The oldest known celebration of what is now Groundhog Day was observed in ancient Ireland and Scotland. Known as Imbolc, it was a commemoration of a cross-quarter day.

The dates of the solstices and equinoxes were known as quarter days — they divided the year into four equal parts. At the time, though, those dates marked the middle of a season, not its beginning or end. Those were marked by the cross-quarter days, which came roughly half way between the quarter days. Imbolc marked the start of spring, and was celebrated with big feasts.

Later, the early Church developed its own cross-quarter celebration. Known as Candlemas, it marked the 40th day of Christmas — the day Jesus was presented at the Temple of Jerusalem. The event came to be celebrated with candles — hence the name.

Both commemorations included references to the weather. A cold, clear day was thought to be a sign of more winter, while a mild, cloudy day was a harbinger of an early spring.

In parts of western Europe, people began using animals as indicators of the weather. That tradition made its way to the U.S. in the 19th century — leading to Groundhog Day.

Script by Damond Benningfield