When Is The First Day Of Summer 2025 Solstice. The first day of summer, also known as the summer solstice, will occur on saturday, june 21, 2025, at 10:42 pm edt. This is the first day of astronomical summer and occurs as.

Summer begins with the solstice on friday, june 20, 2025, marking the astronomical first day of summer in the northern hemisphere. 21.for those north of the equator, which is all of the united states, the solstice marks the.