First Day Of Summer Day 2024. When is the first day of summer? 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.
The first day of summer is also known as the summer solstice, and in 2024 it happens on thursday, june 20 at 4:51 p.m. Is it really the longest day of the year?