Imbolc, Bride, Candlemas, Groundhog Day, usually celebrated on February 2nd in the Northern Hemisphere, (but occasionally on the 1st), halfway between Winter and Spring.
The days are getting longer, and hints of spring are appearing. Sometimes Snowdrops (Galanthus nivalis) can be found peeking through the snow, and ewes begin to lactate. It is considered to be a day of good fortune.