First Day Of Summer 2025 Nz Usa. Summer begins with the solstice on thursday, june 20, 2025, marking the astronomical first day of summer in the northern hemisphere. โthe summer solstice occurs at the moment the earth's tilt.
This year the summer will start on thursday june 20, 2025 (day of the summer solstice) and will end on sunday september 22, 2025 with the autumnal equinox. The astronomical start to summer.