When Was The First Day Of Summer 2024. The true solstice will arrive in the northern hemisphere at exactly 4:51 p.m. In 2024, the summer solstice will occur on june 20, at 20:51 gmt in the northern hemisphere, and on december 21, at 09:20 gmt in the southern hemisphere.

On that day, the autumnal equinox will occur, marking the beginning of fall. This is the longest day of the year and marks the start of.