The shortest day of the year is the winter solstice. But the earliest sunset is not on that day — in London it falls around 12 December, more than a week earlier, and the latest sunrise lands around 30 December, more than a week later. Every city page on this site shows both dates, and the gap is different everywhere.
A solar day is not 24 hours
Our clocks run on a day of exactly 24 hours. The sun does not. The interval between one solar noon and the next changes through the year, by up to about 30 seconds either side, for two reasons.
The first is that Earth’s orbit is an ellipse, so we move faster when we are closer to the sun — which, for the northern hemisphere, is in early January. The second is that Earth’s axis is tilted, so the sun’s apparent motion is not parallel to the equator and its east–west component varies. Together these make solar noon drift against clock noon by up to a quarter of an hour across the year.
What that does to sunrise and sunset
Near the December solstice the solar day is slightly longer than 24 hours, so solar noon creeps later by around 30 seconds a day. Sunrise and sunset both slide later with it.
Meanwhile the day itself is still shortening, which pushes sunrise later and sunset earlier. Around the solstice that shortening nearly stops — the day length changes by seconds, not minutes. So for a couple of weeks the drift dominates: sunset starts getting later while sunrise is still getting later too, and the darkest evening has already passed.
How far apart they are depends on where you are
Nearer the equator the day length barely changes at all in December, so the drift dominates for longer and the gap is bigger — in Miami the earliest sunset comes nearly three weeks before the solstice. At high latitudes the day is shortening fast right up to the solstice, the drift is overwhelmed, and the gap shrinks to a few days.
The same thing happens in reverse in June: the latest sunset comes a few days after the summer solstice, and the earliest sunrise a few days before it.
Where to see it
Open any city page and look at the four dates under the year ribbon: longest day, shortest day, earliest sunset, latest sunrise. The last two are never the same as the first two, and the page says how many days apart they are in that city.
