When Is The First Day Of Summer 2025 Usa Time. The first day of summer arrives with the solstice this year on thursday, june 20, 2025 at 4:51 p.m. Astronomical summer officially arrives in the northern hemisphere — amidst a heat wave — at 4:51 p.m.

When is the first day of summer 2025. The first official day of summer astronomically for 2025 is thursday, june 20, which is when the northern hemisphere has the longest day of the year, according.