The shortest day of year is approaching: What you need to know about the winter solstice

As the nights grow longer and temperatures continue to drop, the 2025 winter solstice is just around the corner. 

The winter solstice marks the shortest day of the year, bringing the least amount of daylight and the longest night.

This year, the winter solstice will occur on Sunday, Dec. 21, at 10:03 am. EST when the Northern Hemisphere is tilted the farthest away from the Sun.

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In cities like Miami, Houston, Atlanta, and Los Angeles, residents will experience at least three to four hours less daylight. New York City and Chicago will see about six hours less, while cities such as Minneapolis, Portland, and Seattle will have roughly seven hours less daylight.

Dates for the winter solstices can very a day or two depending on when the Earth makes one full revolution around the sun. This is why there is a leap year every four years.  

For recordkeeping purposes, meteorologists and climatologists recognize Dec. 1 as the first day of winter. But for those who follow the astronomical seasons, the winter solstice marks the first day of winter.

Astronomical seasons are based on Earth’s position relative to the sun as the planet makes its annual rotation around the closest star.

Astronomers consider the winter solstice the first day of winter because the 23.5-degree tilt of the Earth causes the Southern Hemisphere to receive the most sunlight while the Northern Hemisphere experiences its coldest months.

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During the winter solstice, the sun’s most direct rays are positioned over the Tropic of Capricorn at 23.5 degrees south latitude. Contrary, the summer solstice, which occurs in June, the sun’s most direct rays align with the Tropic of Cancer at 23.5 degrees north latitude.

During the equinox in March and the autumnal equinox in September, the equator aligns directly with the Sun. At these times, everywhere on Earth experiences 12 hours of daylight and 12 hours of night because the sun rises due east and sets due west.

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In the summer, the sun rises in the northeastern sky and sets in the northwestern sky, resulting in long days and short nights. On the summer solstice, the sun reaches its highest and northernmost point in the sky at solar-noon. This provides the most direct solar radiation of the year, causing increased heating of the Earth’s surface and warmer temperatures.

In the winter, the sunrise is in the southeastern sky, and the sunset is in the southwestern sky, which is a much shorter path across the Northern Hemisphere sky. The solar-noon sun angle is the lowest and farthest south in the sky on the winter solstice. 

This means the Northern Hemisphere has had the least direct solar radiation of the year, creating colder temperatures and longer nights.  

However, once the winter solstice passes, the days slowly begin to get longer as winter progresses. The added daylight starts small, only a few seconds at first. But within a few months, the Northern Hemisphere will reach the summer solstice again.