How Long After Sunset Does It Get Dark?

The short answer is that darkness arrives 21 to 30 minutes after sunset for most people on Earth, because most people live between the equator and about 45 degrees of latitude. Move further from the equator and the wait gets longer. Move far enough and it never arrives at all.

That range is wide enough to be useless if you are trying to plan something, so here is the number for real places rather than an average.

The pattern is the point. From Nairobi at 1°S to London at 51°N the wait nearly doubles, and it keeps climbing until it stops meaning anything: above the Arctic Circle in June there is no darkness to wait for.

What "dark" means here

There is no single moment when the sky switches off, so somebody had to draw a line. The convention is civil twilight, which ends when the centre of the sun sits 6 degrees below the horizon. It is a well-chosen line: it is roughly the point at which you can no longer read outside without a light, and the brightest stars and planets have appeared.

Two more lines follow it. Nautical twilight ends at 12 degrees, historically the point where the horizon becomes too indistinct for a sextant. Astronomical twilight ends at 18 degrees, below which the sun contributes nothing measurable to the sky and faint objects become visible.

For the question most people are actually asking — how long have I got before I need a torch — civil twilight is the right line, and it is what the table above uses.

Why latitude decides

The sun does not fall out of the sky vertically. It travels along a circle tilted with respect to the horizon, and the angle of that tilt is what changes with latitude.

At the equator the sun's path is close to perpendicular to the horizon. It goes down like a lift, crosses those six degrees quickly, and darkness follows almost immediately. Twenty-one minutes, near enough, all year round.

At high latitude the path is shallow. The sun slides along at a low angle rather than dropping through it, taking much longer to cover the same six degrees of altitude. In Reykjavík in June it never covers them at all: the sun dips below the horizon and starts rising again while still inside civil twilight, and the sky holds a dusk glow until morning.

Why it also changes with the season

Look along any row of the table and the three columns differ. London gets 36 minutes today, 48 in late June and 40 in late December.

The tilt of the sun's path against the horizon is not fixed for a given place; it varies through the year as the sun's declination changes. Near the solstices the sun's daily arc is at its most oblique relative to the horizon at mid-latitudes, so the crossing takes longer. The effect is small near the equator — Nairobi varies by two minutes across the whole year — and large enough to matter above 50 degrees.

The southern hemisphere mirrors it exactly. Sydney's longest twilight falls in December, Wellington's in December, Ushuaia's most dramatic figures in June and December swap over compared with Europe.

What this means in practice

If you are photographing, the useful light does not stop at sunset. Blue hour occupies roughly the last third of the interval in the table, and in most cities that is 10 to 15 minutes of the most balanced light of the day, when the sky and artificial lighting are close enough in brightness to expose together.

If you are walking or climbing, the table is your margin. Twenty-one minutes is not much of one. In the tropics the transition from comfortable to genuinely dark is fast enough to catch people out, and it is a recurring theme in mountain rescue reports from equatorial regions.

If you are stargazing, civil twilight is only the start. You want astronomical twilight to end, which takes roughly three times as long. In London in June it never does.

Doing it for your own location

Every city page on this site carries the exact figure for that place and today's date, along with the full sequence: sunset, civil dusk, nautical dusk, astronomical dusk. The monthly table shows how each of them moves day by day.

The rule of thumb, if you want to carry one in your head: take your latitude, halve it, and call that the number of minutes. At 50 degrees you get 25 — the real answer for London today is 36, so the rule is rough, but it fails in the safe direction near the equator and only breaks down badly past 55 degrees, where you should be looking the number up anyway.

The awkward cases

Above about 60 degrees the question stops having a single answer for part of the year.

In Reykjavík, civil twilight never ends between late May and late July. There is a sunset, and then there is not darkness — the sun tracks just below the horizon and comes back up. Locals call it the bright nights, and it is one of the reasons Iceland fills with visitors in June.

In Longyearbyen at 78°N the sun does not set at all from 19 April to 24 August, and then does not rise from 27 October to 15 February. In between there are a few weeks where the ordinary question makes sense, and the rest of the year it does not.

We report these as what they are rather than printing a time that does not exist. If you look up a polar town on this site in midsummer, the page will tell you there is no sunset today and give you the date the sun returns.