Imbolc, which falls at the beginning of February, is one of the cornerstones of the Celtic calendar. For rural Highlanders the success of the new farming season was of great importance. As winter stores were getting low, Imbolc rituals were performed to ensure a steady supply of food until the harvest six months later. Eventually, Christianity swallowed it, like it has done with so many old festivals. Imbolc became Candlemass and the goddess of light and fire, Bridhe, became St Brigid.
Weather divination was vitally important to just about everyone who relied on farming to survive back in the day. It is said that on Imbolc, the goddess of winter, Cailleach or Beira, goes to gather her firewood. The legend states that if she wants to linger longer in the world before retreating for the year, she will make the day bright and sunny, so she can gather more wood. So, if Imbolc is sunny and an animal, like a badger, snake or, say, groundhog, peeks out of a winter burrow and sees their shadow, that means winter will last longer.
A Gaelic proverb:
Thig an nathair as an toll
Là donn Brìde,
Ged robh trì troighean dhen t-sneachd
Air leac an làir.
The serpent will come from the hole
On the brown Day of Bríde,
Though there should be three feet of snow
On the flat surface of the ground