Beginning Of Summer 2025 Start Date. The beginning of summer marks the longest day of the year and the start of the summer season in the uk. For those of us in the northern hemisphere, the earth tilts mostly toward the sun during this time.
Summer starts at the moment when the sun is farthest north: The first day of summer arrives with the solstice this year on friday, june 20, 2025, 10:42 p.m.