Summer Solstice 2025 United States Time. 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. It also lists astronomical sunrise and sunset timings on summer.
You can use the us holiday calendar and date calculator to plan this and other important national,. It marks the longest day of the year and the arrival of the summer season