Old Farmer’s Almanac
The winter solstice date is Saturday. So, what is the winter solstice, and why does it happen?
When is the Winter Solstice?
The first day of winter in the Northern Hemisphere is marked by the winter solstice, which occurs at 3:21 a.m. CST Saturday.
For the Northern Hemisphere, the winter solstice occurs every year on Dec. 21 or 22. (The Southern Hemisphere’s winter solstice occurs in June.)
The winter solstice is the day with the fewest hours of sunlight throughout the year, making it the “shortest day” of the year. Thankfully, after we reach the winter solstice, the days begin to grow longer and longer again until we reach the summer solstice — the first day of summer and the longest day of the year.
Think of it this way: Although the winter solstice means the start of winter, it also means the return of more sunlight. It only gets brighter from here.
What is the Winter Solstice?
The winter solstice marks the official beginning of astronomical winter (as opposed to meteorological winter, which starts about 3 weeks before the solstice).
It occurs once a year in each hemisphere: once in the Northern Hemisphere (in December) and once in the Southern Hemisphere (in June).
It marks the start of each hemisphere’s winter season. When one hemisphere is experiencing its winter solstice, the other is simultaneously experiencing its summer solstice.
This is all thanks to Earth’s tilted axis, which means that at the solstice, half of Earth is pointed away from the Sun, and the other half is pointed towards it.
We often think of the winter solstice as an event that spans an entire calendar day, but the solstice actually lasts only a moment. Specifically, it’s the exact moment when a hemisphere is tilted as far away from the sun as possible.
The winter solstice is significant across various cultures, signaling the changing of the seasons. Some ancient peoples even marked the solstice using huge stone structures, like Newgrange in Ireland.
In some cultures, the solstice traditionally marked the midway point of the season rather than the start of it, which explains why holidays such as Midsummer Day are celebrated around the first day of summer.
What happens on the Winter Solstice?
On the day of the winter solstice, we are tilted as far away from the sun as possible, which means that the sun’s path across the sky is as low in the sky as it can be.
Think about the daily path of the sun: It rises in the east and sets in the west, arcing across the sky overhead. During the summer, the Sun arcs high in the sky, but during the winter, it arcs lower, closer to the horizon.
How can we observe the effects of solstice ourselves? On the solstice day, stand outside at noon and look at your shadow. It’s the longest shadow that you’ll cast all year! Do this again on the day of the summer solstice, and you’ll see almost no shadow.
The sun’s changing path
Another way to think of this is that on the day of the solstice, the sun’s path reaches its most southerly point in the sky. For those of us in the Northern Hemisphere, this means that the Sun’s path is as low in the sky as it can get—even at “high noon.”
In the Southern Hemisphere, it’s the opposite: The sun’s path will be high in the sky on the winter solstice — directly overhead at noon at the latitude called the Tropic of Capricorn, which is an imaginary line that circles the Earth, running through parts of South America, southern Africa and Australia.
Winter forest sunset
The word solstice comes from the Latin sol (“sun”) and sistere (“to stand still). So, loosely translated, it means “sun stands still.” Why? The sun’s path across the sky appears to freeze for a few days before and after the solstice. The change in its noontime elevation is so slight that the Sun’s path seems to stay the same or stand still.
The day after the winter solstice, the sun’s path begins to advance northward again, eventually reaching its most northerly point on the day of the summer solstice.
Then, as summer advances toward winter, the points on the horizon where the sun rises and sets advance southward each day; the high point in the Sun’s daily path across the sky, which occurs at local noon, also moves southward each day. It’s a never-ending cycle.
Common questions about the Winter Solstice
The winter solstice is the shortest day of the year. Is it also the coldest?
The day of the winter solstice is the shortest day of the year, which means that it’s the day in which we experience the least amount of daylight.
Logically, it would make sense to assume that this is also the coldest day of the year since we are exposed to less warmth-giving sunlight on this day than at any other time. But this is not true.
Many factors affect a location’s temperature on any given day, including altitude, snow cover, and large-scale weather patterns. Snow cover, for example, partially blocks solar radiation from being absorbed by the Earth, resulting in less heat being released and an overall drop in temperature. Because of these factors, it’s impossible to point to the same date year after year and call it the coldest day.
In the United States, the coldest days of the year tend to occur between mid-December and late January, so while it’s certainly possible that the coldest day of the year could also be the day of the winter solstice, that’s not usually the case.
Is the winter solstice really the start of winter?
There is not a black-and-white answer to this question — it depends on which definition of “winter” you follow:
• Astronomical winter begins at the winter solstice and ends at the spring equinox. Astronomical seasons are based on the position of Earth in relation to the sun.
• Meteorological winter (in the Northern Hemisphere) starts on Dec. 1 and ends on Feb. 28 (or 29). Meteorological seasons are based on the annual temperature cycle and climatological patterns observed on Earth.
Because an almanac is traditionally defined as a “calendar of the heavens,” The Old Farmer’s Almanac follows the astronomical definition of the seasons, which states that each of the four seasons starts on a solstice or equinox.
However, that doesn’t mean that the meteorological definition is incorrect. It is important for meteorologists to be able to compare climatological statistics for a particular season from one year to the next — for agriculture, commerce, and a variety of other purposes. Thus, meteorologists break the seasons down into groupings of three months. Meteorological winter starts on December 1 and includes December, January, and February.
Did you know? For the ancient Celts, the calendar was based around the solstices and equinoxes, marking the Quarter Days, with the mid-points called Cross-Quarter Days. Learn more about the Celtic calendar.
Was Stonehenge Built to Celebrate the Winter Solstice?
One famous ancient marker is Stonehenge in England. Due to the alignment of the stones, experts acknowledge that the design appears to correspond with the solstices.
One theory is that the area was used as a temple to worship the sun and/or as a type of astronomical observatory.
