Although Groundhog Day, Imbolc, or whatever one wishes to name it is celebrated on February Second, from an astronomical viewpoint the mid-point between Winter Solstice and Spring Equinox should come a tad later. In my Donzalo novels (available, of course, from Arachis Press), it is called the Feast of Awakening and is observed today, February 4.
I prefer to see this day as the beginning of Spring, rather than the equinox. That, I would call Mid-Spring. One may, of course, begin the seasons whenever one chooses — there is no 'official' start in this country, though it could be noted that meteorologists, as well as some nations, begin Spring on March First.
So, a Happy Feast of Awakening to all!