June 1 marks the start of #MeteorologicalSummer, which is different than the start of astronomical summer on June 21.

"You may have noticed that meteorologists and climatologists define seasons differently from “regular” or astronomical spring, summer, fall, and winter. So, why do meteorological and astronomical seasons begin and end on different dates?" #NOAA

https://www.ncei.noaa.gov/news/meteorological-versus-astronomical-seasons