I've never understood the way we mark our seasons. For example, after the official beginning of summer, the days are getting shorter. That never seemed fair to me as a kid. Shouldn't summer be full of lengthening days? I much prefer the way the Druids kept track of seasons. They used cross quarter days to mark the change in seasons; days that are halfway between the four astronomical events that we use to define the seasons.
Let's start with the fall equinox. Equinox literally means equal nights. All over the earth, the night and day each are 12 hours long. And it's the beginning of our autumn. The next change is the winter solstice. On this day, winter begins and on the first day of winter -- ta da! -- the days are getting longer. Now the day halfway between the autumn equinox and the winter solstice is a cross quarter day. That day for the Druids was the beginning of their winter, New Years Day, and their most significant holy day.
We borrowed this from the Druids, and celebrate it as Halloween. So by this reckoning, the winter solstice is midwinter, not the beginning of winter. That makes a lot more sense.
Halfway between the winter solstice and spring equinox is the next cross quarter day. We celebrate this much lighter holiday as Groundhog Day. For the Druids, it was first day of spring. Therefore, the vernal equinox was the middle of spring. Halfway between the spring equinox and the summer solstice is May Day. This commemorates the union of male and female energy, and was the beginning of the Druid summer. So June 22 is Midsummer Day, which is what we call it sometimes.
Now the cross quarter day between the summer solstice and the fall equinox is the one holiday we do not acknowledge in our culture. Lammas -- which literally means loaf mass -- was the day to bake the first loaf of bread from the first harvest of grain.