You might’ve already thought it was summer, but astronomically speaking, the first day of summer is this Sunday, June 21.
There are actually two starts to the season: the meteorological start is June 1, which breaks up seasons into three-month blocks, and the astronomical start falls on June 21, where it’s entirely dependent on the Earth’s tilt from the sun.
Also known as the summer solstice, June 21 is the longest day of the year in the Northern Hemisphere. In the Southern Hemisphere, it’s the shortest day.
The summer solstice occurs when Earth’s top half tilts closest to the sun, officially beginning at 3:24 a.m. local time.
