When Is Summer Equinox 2024. Thursday, june 20 is the official first day of northern astronomical summer for 2024 — summer solstice — which is the longest day of the year for this half of the planet. At that moment, the sun will.

When do the four seasons start in 2024—for spring, summer, fall, and winter? In 2024, the summer solstice will occur at 4:50 p.m.