Summer 2024 Date In Usa. 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. This is the longest day of the year and marks the start of summer in the northern hemisphere.

March 19, 2024 (vernal equinox) summer: 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.