Summer Months Calendar 2024. This is the longest day of the year and marks the start of summer in the northern hemisphere. Starts on thursday, june 20 at 4:51 pm, and ends on september 22 at 8:44 am.

The longest day of summer is the summer solstice, which marks the first day of astronomical summer. Imdb is the world’s most popular and authoritative source for movie, tv and celebrity content.