Winter Equinox 2025. Winter solstice 2025 (beginning of astronomical winter) on the day of the winter (december) solstice, the sun passes through the southernmost point of the ecliptic, that is, as far as. Winter 2025 starts on sunday, december 21st in the northern hemisphere, with the first day of winter being the shortest daylight day of the year with the earth's axis having reached its furthest tilt away from the sun and.

The vernal equinox marks the beginning of astronomical spring, while the autumnal equinox marks the beginning of autumn. Naval observatory’s astronomical information center (navy.mil).