Solstice 2025 Summer. In addition to being the longest day of the year, it’s 6 hours and 24. I n 2025, june 20 marks the summer solstice, the first official day of astronomical summer.
— thursday, june 20 is the official first day of northern astronomical summer for 2025 — summer solstice — which is the longest day of the year for this half of the. The summer solstice occurs in june in the northern.