The celebration, which began as a Pennsylvania German custom in southeastern and central Pennsylvania in the 18th and 19th centuries, has its origins in ancient European weather lore, wherein a badger or sacred bear is the prognosticator as opposed to a groundhog. It also bears similarities to the Pagan festival of Imbolc, the seasonal turning point of the Celtic calendar, which is celebrated on February 1 and also involves weather prognostication. and to St. Swithun's Day in July.
An early American reference to Groundhog Day can be found in a diary entry, dated March 5, 1841, of Berks County, Pennsylvania, storekeeper James Morris:
In Scotland the tradition may also derive from an English poem:
As the light grows longer
The cold grows stronger
If Candlemas be fair and bright
Winter will have another flight
If Candlemas be cloud and rain
Winter will be gone and not come again
A farmer should on Candlemas day
Have half his corn and half his hay
On Candlemas day if thorns hang a drop
You can be sure of a good pea crop
mbolc (also Imbolg or Oimelc), or St Brigid’s Day (Scots Gaelic Là Fhèill Brìghde, Irish Lá Fhéile Bríde, the feast day of St. Brigid), is an Irish festival marking the beginning of spring. Most commonly it is celebrated on February 1 or 2 (or February 12, according to the Old Calendar), which falls halfway between the Winter Solstice and the Spring Equinox in the northern hemisphere.
The festival was observed in Gaelic Ireland during the Middle Ages. Reference to Imbolc is made in Irish mythology, in the Tochmarc Emire of the Ulster Cycle. Imbolc was one of the four cross-quarter days referred to in Irish mythology, the others being Beltane, Lughnasadh and Samhain. It has been suggested that it was originally a pagan festival associated with the goddess Brigid, who was later Christianised as St. Brigid.
In the 20th century, Imbolc was resurrected as a religious festival in Neopaganism, specifically in Wicca, Neo-druidry and Celtic reconstructionism.
Irish imbolc derives from the Old Irish i mbolg "in the belly". This refers to the pregnancy of ewes. A medieval glossary etymologizes the term as oimelc "ewe's milk".
Since Imbolc is immediately followed (on 2 February) by Candlemas (Irish Lá Fhéile Muire na gCoinneal "feast day of Mary of the Candles", Welsh Gŵyl Fair y Canhwyllau), Irish imbolc is sometimes rendered as "Candlemas" in English translation; e.g. iar n-imbulc, ba garb a ngeilt translated as "after Candlemas, rough was their herding". -Wikipedia.com