First Day Summer 2024 Date. 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. This year's summer solstice will arrive this thursday on june 20 for the northern hemisphere, according to nasa.

That also happens to be the summer solstice, aka the start of summer. The true solstice will arrive in the northern hemisphere at exactly 4:51.