First Day Of Summer 2024 Time. When is the first day of summer 2024? Usually, when we talk about the first day of summer, we are referring to the astronomical summer which is defined by the earth's axis and orbit around the sun.

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. The first day of summer this year is thursday, june 20, 2024, per the almanac.