Why the earliest sunset is not on the shortest day

October 11, 2026 · 4 min read

Most people assume that the darkest evening of the year falls on the winter solstice, around 21 December, when the Northern Hemisphere has its shortest day. The calendar disagrees. The earliest sunset arrives more than a week before the solstice, and the latest sunrise more than a week after it.

The numbers for this winter

Calculated with the standard sunrise and sunset rule for city centres:

The shortest day, 21 December, sits between the two dates in every case. On that day neither the sunset nor the sunrise is at its extreme; the day is simply shortest because both are close to their extremes at once.

Solar noon drifts through the year

The explanation lies in solar noon, the moment the sun is highest in the sky. If the Earth moved around the sun at a constant speed, with its axis upright, solar noon would arrive at the same clock time every day. Neither is true.

• The Earth’s orbit is slightly elliptical. In early January the Earth is closest to the sun and moves fastest along its orbit, so each day it has to turn a little further to bring the sun back to the meridian.
• The Earth’s axis is tilted by about 23.4°. Near the solstices, this tilt makes the sun’s apparent motion along the sky run more nearly parallel to the celestial equator, which also stretches the solar day.

Together these effects make solar days in December about 30 seconds longer than 24 hours. Clock days stay at exactly 24 hours, so solar noon slips later on the clock by about half a minute each day through December. The difference between clock time and sun time over the year is called the equation of time.

How that shifts sunrise and sunset

Around the solstice, day length changes very slowly: a few seconds a day. Meanwhile solar noon is moving later by about 30 seconds a day. Sunset is roughly “solar noon plus half the day length”, so when day length barely shrinks but solar noon keeps sliding later, sunsets start getting later even before the shortest day. Sunrise, “solar noon minus half the day length”, keeps getting later for a while after the solstice for the same reason.

The size of the gap depends on latitude. Closer to the equator, day length changes more slowly through December, so the equation of time dominates for longer, and the earliest sunset falls earlier, as in New York, at about 40.7° north, where it comes on 7 December.

The same effect in summer

The pattern repeats around the June solstice, mirrored. Calculated for Paris in 2027, the earliest sunrise comes on about 12 June, at 05:46, and the latest sunset on about 23 June, at 21:58. The longest day, 21 June, again sits between them. In summer the equation of time changes more slowly than in December, so the gap between the dates is smaller, about eleven days rather than three weeks.

In the Southern Hemisphere

South of the equator the seasons are reversed, and so is the pattern. In Sydney, the earliest sunset of the 2027 winter comes on about 9 June, at 16:52, while the latest sunrise is on about 29 June, at 07:01. The shortest day, 21 June, falls between them, exactly as 21 December does in Paris.

How large the drift is

The equation of time is not a small correction. Over the coming year it reaches its largest positive value, about 16.4 minutes, around 3 November 2026: the sun crosses the meridian that much earlier than the clock suggests. Its largest negative value, about −14.2 minutes, comes around 11 February 2027. Sundials have always shown this difference; many old ones carry a small table or a figure-of-eight curve, the analemma, to convert sun time to clock time.

Time zones add a second, fixed offset. Paris keeps Central European Time, set for a meridian 15° east of Greenwich, although the city lies at about 2.3° east, so its solar noon in winter falls between about 12:35 and 13:05 on the clock, depending on the date. That is why Paris winter mornings feel late, and why the latest sunrise, at 08:44, is later than in London despite London lying further north.

What it means in practice

Two practical consequences follow. If you are planning a walk after work in December, the light improves from mid-month, not from the solstice. And if you rely on daylight in the morning, for a commute or a school run, the darkest mornings come in the first days of January.

For anyone who dislikes dark afternoons, there is good news well before Christmas: from mid-December the evenings are already getting lighter. Mornings, though, keep getting darker into the first days of January.

It also means that “the shortest day” and “the darkest evening” are two different dates to mark. If you want to dedicate a sunset to someone in winter, the exact time at their place matters more than the calendar date. The Sunset is calculated for the precise point you choose, and the gift wizard shows the time before you pay.