World Longest Day 2025 Calendar. Online list of all official holidays and public holidays in the world for 2025. 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.
As an hr you need to plan in advance some initiatives and big dates to celebrate. The timing shifts because it depends on when the sun reaches its northernmost point from the celestial equator.