cross-quarter days

I've long thought it a little counterintuitive that seasons are said to begin and end on the equinoxes and solstices—after all, wouldn't you naïvely expect the longest day of the year, the summer solstice, to be the middle of summer (midsommar!) and not its beginning? (I would say that the seasons and the length of the days are 90 degrees out of phase... )

I learned on the radio today that the days midway between solstices and equinoxes are called cross-quarter days, and in many cultures do mark the boundaries of the seasons.

Today is November's cross-quarter day, marking the middle of astronomical autumn, and the first day of traditional winter.