First Day Of Summer 2024 Date And Time. Today (june 20) the summer solstice — the longest day of the year in the northern hemisphere — will begin, and it will be the earliest solstice in 228 years. The first day of summer in the northern hemisphere will be on june 20, 2024.

Edt (2051 gmt), and the summer solstice for the southern hemisphere. Summer begins with the solstice on thursday, june 20, 2024, marking the astronomical first day of summer in the northern hemisphere.