Today is September 1. It’s the first day of meteorological autumn. Of course, the autumnal equinox is still some three weeks away. And it does still feel like summer outside (and will for a little while longer). Traditionally, we have marked the change in seasons from equinox to solstice to equinox to solstice. But perception is as much a factor in marking the seasons as the earth’s tilt. So we have what we call meteorological autumn, winter, spring and summer, which begin on the 1st of the month in which we experience an equinox or solstice. The two are offset by about three weeks. Meteorological winter begins on December 1, with the winter solstice coming approximately three weeks later. Meteorological spring begins March 1. And meteorological summer starts June 1. The reasoning is easy to explain. September feels more like autumn than summer. December feels more like winter than autumn. March feels more like spring than winter. And June feels more like summer than spring. So, yes, it’s still summer according to the astronomical calendar. But practically, today is the first day of autumn.