The first day of winter in 2025 (astronomical winter in the Northern Hemisphere) is Sunday, December 21, 2025.

Quick Scoop

  • Astronomical winter 2025 : Starts on Sunday, December 21, 2025, when the winter solstice occurs and the Northern Hemisphere is tilted farthest away from the sun.
  • Solstice timing : The winter solstice in 2025 happens on December 21 at about mid‑day UTC, making that date the official first day of winter in many calendars.
  • Why it matters : The solstice marks the shortest day and longest night of the year, after which daylight slowly begins to increase again toward summer.

In everyday talk, many people say “winter starts December 21” because that is when the solstice flips the year from darkening days back toward the light again.

Information gathered from public forums or data available on the internet and portrayed here.