When Is The 2025 Summer Solstice. Why is the summer solstice the longest day of the year? Summer 2025 starts on friday, 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.

In 2025 the june solstice in europe will be on saturday , 21st of june 2025, around 04:41 pm; Summer 2025 starts on friday, 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.