When Does Summer Start 2025 Usa. To find out why the seasons occur, visit this page: 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.

When do the four seasons start in 2025—for spring, summer, fall, and winter? United states 2025 holiday calendar with all major holidays and observances.