First Day Of Summer 2024 Calendar Dates 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. This year, the first day of summer, also known as the summer solstice, is thursday, june 20.

When is the first day of summer? Summer begins with the summer solstice, thursday, june 20, 2024, 4:51 p.m.