Page "Summer" Paragraph 2

From the astronomical perspective, days continue to lengthen from equinox to solstice and summer days progressively shorten after the solstice, so meteorological summer encompasses the build-up to the longest day and a diminishing thereafter, with summer having many more hours of daylight than spring.

Solstices and equinoxes are taken to mark the mid-points, not the beginnings, of the seasons.

Midsummer takes place over the shortest night of the year, which is the summer solstice, or on a nearby date that varies with tradition.