When it comes to climate and weather, the seasons start at different times of year depending on where one is on Earth. Astronomically speaking, though, the first day of spring happens on the vernal equinox; the first day of summer happens on the summer solstice; the first day of fall happens on the autumnal equinox; and the first day of winter happens on the winter solstice.

When it comes to official weather statistics, the seasons are considered to be as follows: winter is December through February; spring is March through May; summer is June through August; and fall is September through November. So, if you hear a report, for example, that “last summer was the hottest on record,” that means June 1 through August 31, and not June 21 through September 21, which is how it is marked on your typical calendar.