How Long After Sunset Does It Get Dark?
The sun goes down and the sky stays bright for a surprisingly long time. That stretch is twilight, and how long it lasts depends almost entirely on where you are. The numbers below are worked out by latitude, and any location page gives the exact times for a specific place.
The short answer: full darkness arrives when the sun reaches 18 degrees below the horizon. Near the equator that takes about 70 minutes after sunset. In New York it ranges from 92 minutes to just over two hours depending on the season. In London in June it never happens at all.
The Three Phases of Twilight
Twilight is split into three bands, each defined by how far the sun has sunk below the horizon. After sunset you pass through them in order.
- Civil twilight: sun from 0 to 6 degrees below the horizon. Bright enough to read outside and to keep working without lights. Photographers know the tail end of it as blue hour.
- Nautical twilight: 6 to 12 degrees. Stars are out, and the horizon line at sea is still faintly visible. That combination is what the name refers to, since it is the window when a navigator can shoot a star against a visible horizon with a sextant. By the end of it, the horizon has gone.
- Astronomical twilight: 12 to 18 degrees. Dark enough for casual stargazing, but the sky still holds a faint glow from sunlight scattering off the very high atmosphere. Faint deep-sky objects stay washed out.
Night begins when astronomical twilight ends, at 18 degrees. Past that point the sun contributes nothing measurable to sky brightness.
Acadia National Park, Maine, well after astronomical twilight has ended. The Milky Way’s dust lanes only show up once the sun is more than 18 degrees down and the sky is genuinely dark. The straight line at left is an aircraft, not a meteor.
One correction worth making, because it gets repeated constantly: astronomical twilight is not the same thing as complete darkness. It is the last phase before it. If a source tells you astronomical twilight is when the sky is fully dark, it has the boundary in the wrong place.
How Long It Actually Takes
The sun sets vertically at the equator and at a slant everywhere else. The farther you are from the equator, the shallower that angle gets, the longer the sun takes to travel those 18 degrees, and the longer you wait for dark.
Minutes from sunset to full darkness, by latitude and season:
| Location | March equinox | June solstice | December solstice |
|---|---|---|---|
| Singapore (1.4°N) | 69 | 75 | 75 |
| Miami (25.8°N) | 77 | 90 | 82 |
| New York (40.7°N) | 92 | 126 | 99 |
| London (51.5°N) | 114 | never | 124 |
| Anchorage (61.2°N) | 153 | never | 176 |
A few things fall out of that table.
Twilight is shortest at the equinoxes, not in winter. The sun’s path is steepest relative to the horizon in March and September, so that is when night arrives fastest. Both solstices are slower.
Summer twilight beats winter twilight at mid-latitudes. New York gets 126 minutes in June against 99 in December, which runs contrary to the common assumption that long summer evenings are just an illusion of the later clock time. They are genuinely longer.
Above roughly 48.5 degrees, the sky stops going fully dark around midsummer. The sun never manages to get 18 degrees down. That threshold catches Paris, Vancouver, Frankfurt, and London.
Push past about 60.5 degrees and even civil twilight fails to end, so it stays light enough to read outside all night. Anchorage and Reykjavik are past that line. St. Petersburg, the city most associated with White Nights, is at 59.9 degrees and misses it by roughly half a degree: the sun bottoms out about 6.6 degrees down in late June, which buys the city a short window of genuine nautical twilight around 1am rather than none at all.
Why Latitude Matters So Much
Sunset in Branson, Missouri
At the equator the sun’s daily track meets the horizon at close to a right angle. It drops straight down and keeps dropping, covering 18 degrees in a little over an hour.
Move north or south and that track tilts. At 40 degrees latitude the sun crosses the horizon at roughly a 50 degree angle near the equinoxes and shallower than that at the solstices. It is still descending at the same rate along its own path, but the vertical component of that motion is smaller, so its depth below the horizon builds slowly.
Take it far enough and the path becomes nearly parallel to the horizon. The sun skims along just underneath it for hours, which is why an Arctic summer night is a long orange smear rather than a sunset.
What Is Sunset, Exactly?
Sunset is the moment the upper edge of the sun’s disk drops below the horizon. Not the center, and not the last of the light.
That definition already includes two corrections. The sun’s disk is about half a degree wide, and the atmosphere bends its light upward by roughly another half degree near the horizon. Add those together and at the official moment of sunset the sun’s geometric center is already about 50 arcminutes below the horizon. You are watching an image of a sun that has technically already set. The math behind that is covered in how sunrise is calculated.
The period before sunset is golden hour, when the low sun angle puts a warm cast on everything.
What Else Changes the Timing
Latitude and season set the bulk of it. Three other things move the edges.
Elevation shifts sunset later without moving the end of twilight. Twilight boundaries are defined by the sun’s true depression angle, which does not care how high you are standing. Sunset does care, because from higher up you see farther over the curve. The net effect is that your window between sunset and dark gets shorter as you climb, which is the opposite of what most people expect. See how elevation affects sunset times for the numbers.
Terrain changes when you lose the sun but not when the sky goes dark. A ridge to your west can take the sun 20 minutes early. Twilight still runs on schedule.
Light pollution changes what you can see, not when it is dark. In a city the sky may never look dark regardless of where the sun is. The phases still happen; you just cannot read them off the sky.
Why So Many Rules Say “30 Minutes After Sunset”
If you have run into that phrase on a hunting regulation, a headlight law, or a park closing sign, it is a fixed stand-in for the end of civil twilight. California’s vehicle code defines darkness as any time from half an hour after sunset to half an hour before sunrise. Texas sets legal shooting hours for game animals over the same bracket, half an hour before sunrise to half an hour after sunset. The appeal is obvious: you can check it against a printed sunset time with no calculation at all.
The substitution is decent across the lower 48. Civil twilight runs 27 to 33 minutes in New York, and about 25 minutes in Miami, so a flat 30 is close enough for a rule that has to fit on a sign.
It falls apart with latitude, in both directions. Civil twilight is only about 21 minutes near the equator, so the half-hour rule hands you 9 minutes of dark you were not expecting. In Anchorage in December it runs 62 minutes, and in London in June it takes 48 minutes, which means the fixed rule cuts you off while it is still comfortably light.
Aviation does not use the shortcut. The FAA defines night as the stretch between the end of evening civil twilight and the beginning of morning civil twilight, computed for the date and place rather than offset from sunset.
So if you are answering “is it still light 30 minutes after sunset,” the honest answer is that it depends on how far you are from the equator and what time of year it is. At mid-latitudes you are right at the edge of usable light. Farther north in summer you have a good while left.
Finding the Times for Your Location
The sunrise and sunset times tool gives you civil, nautical, and astronomical twilight for any location, which is more precise than working from a rule of thumb. Rules of thumb are the problem with this topic. The often-repeated “about an hour to get dark” is roughly correct in Singapore and wrong nearly everywhere else.
If you are timing an evening hike, civil twilight is your deadline for seeing the trail without a headlamp. If you are setting up a telescope, the number you want is the end of astronomical twilight. For photography, the good light usually falls in the 20 to 30 minutes after sunset, during civil twilight and the start of nautical.
Frequently Asked Questions
How long after sunset does it get really dark?
Between about 70 minutes and never, depending on latitude and date. Near the equator it is roughly 70 minutes year round. At 40 degrees north it runs 92 minutes at the equinoxes and 126 minutes in June. Above about 48.5 degrees the sky does not reach astronomical darkness at all for several weeks around midsummer.
How long after sunset is it dark in the UK?
London takes about 114 minutes to reach full darkness at the equinoxes and 124 minutes around the December solstice. Between roughly May 23 and July 21 it never gets there at all, because the sun stays inside 18 degrees of the horizon all night. Scotland loses astronomical darkness for longer: Edinburgh from early May to early August, Inverness from the end of April to mid-August.
Is it still light 30 minutes after sunset?
Usually just barely, at mid-latitudes. Thirty minutes is roughly when civil twilight ends at 40 degrees north, which is the point where you stop being able to read outdoors or make out a trail without a light. Near the equator civil twilight is over in about 21 minutes, so 30 minutes in is already darker than that. In London in June you still have almost 20 minutes of civil twilight left at that point.
Does it get dark faster in winter?
At mid-latitudes, yes, and by a wide margin. New York goes from sunset to full darkness in 99 minutes in December against 126 in June. The fastest twilights of all are at the equinoxes in March and September, when the sun’s path meets the horizon at its steepest angle.
Why does it stay light so long after sunset in summer?
The sun is not dropping straight down. In summer at mid and high latitudes its path is tilted well away from vertical, so it takes much longer to travel the 18 degrees below the horizon that separate sunset from true darkness. That is a real effect on top of the later clock time, not an illusion caused by it.