Summer 2025 Start Date Usa. Summer 2025 starts on thursday, 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. When is the first day of summer?
27 rows the season change dates are based on the spring and fall equinoxes as well as the summer and winter solstices. What are the dates for the four seasons in 2025?