If you follow this blog regularly, you know from previous posts that the meteorological seasons start at the beginning of months and not in mid-month as the astronomical calendar does. So June 1 marks the beginning of summer for meteorologists and climatologists. The choice of using the beginning of a calendar month is both practical (since historically meteorological calculations were done using monthly climate data) and realistic (since the warmest 90 day period corresponds more to the June through August calendar period than the 90 days following the beginning of astronomical summer). Hope you have a fantastic season!