First Day Of Summer 2025 Calendar. This is the first day of summer (summer solstice) in the northern hemisphere and the first day of winter (winter solstice) in the southern hemisphere. Summer is celebrated every year on june, 01.

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. Next summer will be on june 1, 2025.