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Monday, December 21 · in 125 days
The shortest day of the year — the winter solstice — is the day when the sun reaches its lowest point in the sky and daylight is at its minimum. In the Northern Hemisphere this falls around December 21 or 22. In the Southern Hemisphere the seasons are reversed, and the shortest day falls around June 20 or 21.
After the winter solstice, the days immediately begin to get longer — slowly at first, then with increasing speed. The solstice is the turning point of the year.
As with the longest day, how little daylight you receive depends on your latitude. Locations near the poles experience the most dramatic shortening; locations near the equator barely notice a difference.
| Location | Latitude | Day length at winter solstice |
|---|---|---|
| Tromsø, Norway | 70°N | 0 h 00 min (polar night — sun does not rise) |
| London, UK | 51°N | ~7 h 50 min |
| New York, USA | 41°N | ~9 h 15 min |
| Singapore | 1°N | ~12 h 03 min |
| Sydney, Australia | 34°S | ~14 h 25 min (their longest day) |
Above the Arctic Circle (66.5°N), the sun stays below the horizon for days or even weeks around the winter solstice — a phenomenon known as polar night. In Tromsø, Norway (70°N), the sun doesn't rise at all for about two months. At the poles themselves, winter night lasts six months.
Despite the gloom, the winter solstice carries a hopeful message: from this day forward, the light returns. The increase is barely perceptible at first — just one or two minutes of extra daylight per day in late December and January. But by February the pace picks up noticeably, and by the time the spring equinox arrives in late March, days are lengthening by three to five minutes every day at mid-latitudes. The cycle continues until the summer solstice in June, when the longest day of the year arrives. Read more about this process in when do the days start getting longer.
Many of the world's most enduring midwinter traditions are rooted in the solstice. The Roman festival of Saturnalia, the Norse celebration of Yule, and the Persian festival of Yalda Night all cluster around the winter solstice — a time when ancient peoples lit fires, feasted, and held vigil against the darkness, celebrating the return of the light. Christmas, which falls just days after the solstice, shares much of this symbolic territory.
In East Asia, the winter solstice is celebrated as Dongzhi (冬至) in China, Korea, and Japan — a time for family gatherings and traditional foods like tangyuan (glutinous rice balls). In Iran, Yalda Night on December 21 is one of the most important nights of the year, when families stay up until midnight reading poetry and sharing pomegranates and watermelons.
If you live south of the equator, your shortest day falls in June, not December. While the Northern Hemisphere marks its winter solstice in December, Sydney and Cape Town are enjoying their longest days. The calendar date of the solstice is the same for everyone on Earth — what differs is which hemisphere is tilted toward the sun.
Use the tool on the homepage to see the exact sunrise, sunset, and day length for your location — on today's date or any other.
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The most useful thing to know about midwinter is that the shortest day is not the darkest evening. In London the earliest sunset arrives around 12 December — more than a week before the solstice — while the latest sunrise does not come until about 30 December.
For the three weeks in between, the two ends of the day move in opposite directions: the evenings are already drawing out while the mornings are still getting darker. If it has ever seemed to you that the light started coming back before Christmas, you were right, and this is why.
The cause is the equation of time — solar noon drifting against clock time by up to about sixteen minutes across the year, because the Earth's orbit is elliptical and its axis is tilted. In December the drift is at its steepest, which is why the split is so pronounced. Further north the effect is smaller relative to the large swing in day length; nearer the equator it dominates.
The shortest day is defined by hours, but what people notice is the angle. At the December solstice the midday sun reaches only about 15° above the horizon in London and about 11° in Copenhagen — low enough that it never clears the buildings on a city street, and low enough that shadows at noon are five times the height of whatever casts them.
That geometry is why midwinter light has such a distinctive quality: everything is lit sidelong, all day, and it never stops looking like late afternoon. It is also why the UV index sits at 0 or 1 for months in northern Europe, and why so little heat arrives even on a clear day — the same energy is spread across a much larger area of ground.
The solstice marks the astronomical start of winter and the middle of the thermal one. Because ground and ocean keep losing more heat each day than they gain for weeks afterwards, the coldest part of the year in maritime northern Europe usually falls in late January or February — a seasonal lag of six to eight weeks. Continental interiors, with less water to buffer them, lag by less.
Older calendars often reflected this better than ours does. Calling late December "midwinter" rather than the start of winter matches what the sun is doing, and the great fire-and-light festivals of the season cluster around it for the obvious reason: it is the point at which the decline stops.
In the northern hemisphere it falls between 20 and 23 December, most often on 21 December. In the southern hemisphere the same date is the longest day of the year.
Because of the equation of time. In London the earliest sunset arrives around 12 December, over a week before the solstice, while the latest sunrise does not come until about 30 December. For those three weeks the evenings are drawing out while the mornings still get darker.
At the December solstice the midday sun reaches only about 15° above the horizon in London and about 11° in Copenhagen. Shadows at noon are around five times the height of whatever casts them.