Summer 2025. When is the summer solstice 2024 and 2025 in the southern and northern hemispheres? The dates given on this page are based on coordinated universal time (utc), which for practical purposes is equivalent to greenwich mean time (gmt).

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. Summer 2025 starts on saturday, june 21, 2025 (in 180 days) and ends on monday, september 22nd 2025 (in 273 days).