What time does it get dark?

The US Naval Observatory defines all three, and the definitions are more practical than they sound.

Sunset is when the top edge of the sun touches the horizon. Air bends the light, so the calculation puts the sun's centre about 0.83° below the horizon at that moment. Street lights may be on. The sky isn't dark.

Civil twilight ends when the sun's centre is 6° down. After that, the Observatory says, you normally need artificial light for ordinary outdoor activities. Floodlit buildings start to look floodlit. This is the point a city night tour actually becomes a night tour.

Nautical twilight ends at 12°. Sailors could still see the horizon to take star sightings before this, which is where the name comes from. To the eye on a city street, it's night. To a camera, the sky has gone from deep blue to black.

There's a fourth, astronomical twilight, which ends at 18°, when scattered sunlight is fainter than starlight. Our calculator stops at nautical. If you're paying for a telescope, though, astronomical dark is the one that counts, and the tours know it.

The gap between them changes with latitude. Near the equator the sun drops almost straight down, so twilight is short: in Singapore in December, 22 minutes from sunset to civil dark. In Edinburgh in June the sun slides sideways along the horizon. Sunset is 9:59 p.m., civil dark 11:01 p.m., and nautical twilight never ends at all, because the sun never gets 12° down.

Mid-month times, 2027, local clock time. "Dark" is the end of civil twilight. Every city page has the full twelve months.

Look at Paris against Rome. Paris is further north, so its days are longer in June, but it's also far to the west of its time zone, so everything happens late. A Seine cruise at 9:30 p.m. in June leaves before sunset. Tokyo is the opposite: Japan doesn't use daylight saving, and it's dark by 7:28 p.m. even at midsummer.

Most ghost walks run at the same clock times all year. The sun doesn't. One of the London Jack the Ripper tours on our list starts at 7:30 p.m. In December that's three hours after dark. In June it's nearly two hours before sunset, and you'll be hearing about Whitechapel in 1888 while people are still sitting outside pubs in daylight.

Is that a problem? For a history-heavy walk, not much. For anything sold on atmosphere, yes. If the booking calendar shows several start times, pick the first one after the city's "dark" time for your month. In summer in northern Europe that often means the last slot of the night, which is fine.

The rule of thumb that works: in Edinburgh, London, Prague, Berlin, Dublin and Amsterdam, any tour from November to February is a night tour. From May to August, almost none are unless they start after about 9:30 p.m., later in Edinburgh. Southern Europe and the American cities are less extreme, but a 7 p.m. June walk in New York or Rome still starts before sunset.

Stargazing tours handle the timing for you, because they live or die by it. The Mauna Kea trips leave in the afternoon so you're at the summit for sunset, and then they come down: the Center for Maunakea Stewardship closes the summit area to visitors 30 minutes after sunset, and anyone staying for stars has to go below Park 2. The telescope part usually happens around 9,000 ft. One of the Tenerife Teide tours starts 40 minutes after sunset, roughly when civil twilight ends there. What the calculator can't tell you is the moon. A bright moon washes out faint stars, and one Sedona operator doesn't run around the full moon at all. Check a moon calendar before you book.

The same goes double for bioluminescent bays. Operators and reviewers agree: new moon good, full moon bad.

Night safaris. Singapore's Night Safari opens at 6 p.m., and Mandai starts the walking trails and the tram at 7 p.m. Sunset in Singapore falls between 6:51 and 7:21 p.m. all year, so a 7 p.m. tram is in twilight and an 8 p.m. one is in full dark. Go later. The park is open until midnight, with last entry at 11:15 p.m.

Costa Rica. Monteverde and La Fortuna are close to the equator, so the dark barely moves: it falls between 5:35 and 6:28 p.m. all year in both towns. That's why the rainforest night walks start at 5:30 or 6 p.m. A 5:30 p.m. walk in June begins in daylight and gets dark around you as you walk. In December the same start is already in twilight.

This is where people get caught. The tours don't move their start times, but the dark moves an hour overnight.

• United States: daylight saving ends at 2 a.m. on Sunday, November 1, 2026, per NIST. Under the rule NIST publishes (second Sunday in March to first Sunday in November), it starts again on March 14, 2027 and ends on November 7, 2027.
• UK: clocks went back on October 25, 2026. In 2027 they go forward on March 28 and back on October 31, according to GOV.UK.
• EU: the same last-Sunday-of-March and last-Sunday-of-October rule, set by Directive 2000/84/EC, so the same dates as the UK.
• No change: Hawaii and Arizona don't use daylight saving (NIST again), which matters for Mauna Kea and Sedona. The time zone database our calculator uses shows no clock change in 2026 or 2027 for Mexico City, Costa Rica, Singapore, Bangkok or Tokyo.

Two practical effects. Right now, the last week of October 2026, Europe has already gone back and the US hasn't, so the London to New York gap is four hours, not five, until November 1. And from March 14 to March 28, 2027, it's the reverse: the US has jumped forward and Europe hasn't. If you're booking a tour from home across the Atlantic in either window, double-check the local time on the confirmation.

The US change in November is also why our New York page shows dark at 6:44 p.m. in mid-October and 5:08 p.m. in mid-November. An hour of that drop is one Sunday morning. The rest is the season.