When Is The Start Of Summer 2025. Learn more about when it starts, the summer solstice and more. When is the first day of summer 2025.
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. This year, the first day of summer, also known as the summer solstice, is thursday, june 20.