On the first of May every year I’m taken back to a memory from my childhood: Me, sitting at my kitchen table with the sun beaming in through the double doors, my Dad opening them wide and announcing the official beginning of summer.
According to the laws of astronomy, the beginning and end of seasons are determined by dates of equinoxes and solstices. There’s a spring equinox, a summer solstice, an autumn equinox, and a winter solstice, the end of one always marking the beginning of the next. Because these dates change every year, so to do the lengths of astronomical seasons. This years summer solstice falls on June 20th, so therein marks the beginning of the astronomical summer. While meteorology also takes notice of equinoxes and solstices when determining the length of a season, by this law the seasons fall not on the day of those equinoxes and solstices, but on the first day of the month during which they happen. So this year, by meteorological standards, summer begins on June 1st.