What Day Is The Summer Solstice 2025. On the summer solstice, when the northern tilt is closest to the sun, we have the longest day, usually june 20 or 21. London the exact moment of the summer solstice in 2025 is 21 june, at 03:42:02.

When is the first day of summer 2025? Summer begins with the solstice on friday, june 20, 2025, marking the astronomical first day of summer in the northern hemisphere.