Northern Hemisphere Winter Solstice Arrives, Signaling Return to Increasing Daylight

The Northern Hemisphere officially commenced astronomical winter on Sunday, December 21, 2025, precisely marked by the Winter Solstice occurring at 15:03 GMT/UTC. This pivotal astronomical event denotes the shortest day and the longest night for all regions situated north of the equator. The phenomenon is fundamentally caused by the Earth's axis maintaining a tilt of approximately 23.5 degrees relative to its orbital plane, positioning the Northern Hemisphere at its maximum lean away from the Sun.

Following this instant, the Sun's apparent movement, which had been tracking southward, appears to pause before initiating its northward trajectory, thus beginning the gradual increase in subsequent daylight hours. This precise timing dictates the commencement of astronomical winter, which, in 2025, is scheduled to conclude on March 20, 2026. This astronomical demarcation contrasts with the meteorological definition of winter, which meteorologists establish using fixed calendar months, beginning on December 1, 2025, and concluding on February 28 or 29, to track the coldest annual period.

Geographical variations in daylight duration across the hemisphere underscore the impact of latitude on solar exposure during this minimum. In London, the shortest day provided approximately 7 hours, 49 minutes, and 42 seconds of daylight, with sunrise near 08:05 and sunset around 15:54 GMT. Further north in John O'Groats, the duration was shorter at 6 hours, 16 minutes, and 54 seconds, while the more southerly location of Truro experienced 8 hours, 1 minute, and 55 seconds of light. Overall, this shortest day represents a reduction of about nine fewer hours of sunshine compared to the peak daylight hours observed during the summer solstice.

Astrophysics expert Dr. Shyam Balaji, affiliated with King's College London, explained that the solstice represents the pause in the Sun's apparent motion before its reversal. The Earth's axial tilt of about 23.5 degrees is the underlying cause, ensuring that the Tropic of Capricorn, located at approximately 23.4 degrees south latitude, receives the Sun's most direct rays at this time, marking summer for the Southern Hemisphere. This annual celestial event serves as a reliable marker in the Earth's orbit, offering a consistent, scientifically defined transition point for the season.