Longest Day Of The Year 2024 Usa Time. It’ll be the longest day of the year north of the equator, and it is the scientific. In this case, it’s the official start to the astronomical summer, which in the northern hemisphere occurs this year on thursday, june 20, at 3:50 p.m.
Here’s why it’s a day early. The longest day of the year falls on either june 20 or 21 every year in the northern hemisphere.