What Date Does Summer Start 2024. 27 rows the season change dates are based on the spring and fall equinoxes as well as the summer and winter solstices. Summer 2024 starts on thursday, june 20th in the northern hemisphere, with the first day of summer being the longest daylight day of the year with the earth's axis having reached its furthest tilt and begins to change directiion back.

The longest day of the year falls on either june 20 or 21 every year in the northern hemisphere. The first day of summer this year is thursday, june 20.