When Does Summer Begin 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 reached its furthest tilt and begins to change directiion back. In 2025, the first day of winter will arrive on dec.

This year’s summer solstice will arrive this thursday on june 20 for the northern hemisphere, according to nasa. The first day of summer is also known as the summer solstice, and in 2025 it happens on thursday, june 20 at 4:51 p.m.