First Day Of Summer 2025 Canada Calendar. In 2025, the summer solstice will occur on june 21, at 02:42 gmt in the northern hemisphere, and on december 21, 2024 at 09:20 gmt in the southern hemisphere. The first day of summer, also known as the summer solstice, will occur on saturday, june 21, 2025, at 10:42 pm edt.

Starting point (mandatory activities in academic units. The summer solstice is also known as the longest day, which is perhaps the most notable feature.