When in the year are days longest?
The first day of summer (on or about June 21 in the Northern
Hermisphere) is the longest day of the year, meaning the most hours
of sunlight. From there, each day is a little bit shorter until you
come to the shortest day, the first day of winter (on or about
December 21). Then they start getting longer again.
The first day of summer is called the Summer Solstice, and the
first day of winter is called the Winter Solstice.