Sunrise and Sunset Times: How Daylight Hours Change Across the World
Sunrise and sunset times affect everything from your morning run to international video calls. A designer in Berlin scheduling a review with a developer in San Francisco needs to know that 9 AM in Berlin is midnight in San Francisco — and that in December, Berlin sees only 8 hours of daylight while San Francisco gets 9.5.
Every city page on World Time Sync now shows live sunrise, sunset, and daylight duration. But understanding why these times change helps you plan better.
Why Daylight Hours Vary
Earth's axis is tilted 23.5° relative to its orbit around the sun. This tilt — not distance from the sun — causes seasons and varying daylight hours:
- Summer solstice (June 20–22): The Northern Hemisphere tilts toward the sun. Longest day in London (16.5h), shortest in Sydney (9.8h).
- Winter solstice (December 21–23): The Northern Hemisphere tilts away. Shortest day in London (7.8h), longest in Sydney (14.5h).
- Equinoxes (March 20, September 22): Equal day and night everywhere (~12h each).
Latitude matters enormously. Near the equator, day length barely changes throughout the year (Lagos: 11.5–12.5h). Near the Arctic Circle, the variation is extreme: in summer the sun never sets (midnight sun), in winter it never rises (polar night).
Daylight Hours by Latitude (June vs December)
| City | Latitude | June Daylight | December Daylight |
|---|---|---|---|
| Singapore | 1.4°N | 12.1h | 12.1h |
| Mumbai | 19.1°N | 13.3h | 10.9h |
| Cairo | 30.0°N | 14.1h | 10.2h |
| New York | 40.7°N | 15.1h | 9.3h |
| Tokyo | 35.7°N | 14.5h | 9.7h |
| Berlin | 52.5°N | 16.7h | 7.9h |
| Oslo | 59.9°N | 18.5h | 6.0h |
| Reykjavik | 64.1°N | 21.0h (nearly all day) | 4.1h |
How Sunrise/Sunset Times Are Calculated
The calculation depends on three factors:
- Latitude — determines the sun's maximum angle above the horizon.
- Day of year — the sun's declination (how far north or south of the equator the sun appears directly overhead) changes daily.
- Equation of time — Earth's elliptical orbit and axial tilt mean solar noon (when the sun is highest) does not always occur at exactly 12:00 on the clock.
The sunrise hour angle is calculated as:
cos(H) = (cos(90.833°) − sin(declination) × sin(latitude)) / (cos(declination) × cos(latitude))
Where 90.833° accounts for atmospheric refraction (the sun appears to rise before it geometrically clears the horizon) and the sun's angular radius. If cos(H) > 1, the sun never rises (polar night). If cos(H) < −1, the sun never sets (midnight sun).
Practical Uses
For remote workers: If you're in London and your team is in New York, scheduling a call at 3 PM London time (10 AM New York) works year-round. But a 5 PM London call is fine in summer (New York still has daylight at noon) but feels like an imposition in winter (New York is dark by 4:30 PM).
For photographers: "Golden hour" — the period shortly after sunrise and before sunset — produces the best natural light. It lasts longer at high latitudes (up to 2 hours in summer in Scandinavia) and shorter near the equator (about 20 minutes).
For travelers: Jet lag is worse when you travel east (you "lose" time) and when daylight patterns change dramatically. Flying from London to New York in winter means arriving in a city with 4 fewer hours of daylight than you left.
FAQ
Where does the sun rise and set first?
The first inhabited place to see the sun each day depends on the date. Around the equinoxes, it's Kiribati (UTC+14). In December, it's parts of New Zealand and Antarctica. In June, it's parts of Russia and Alaska near the International Date Line.
Why does the earliest sunset not coincide with the winter solstice?
Because of the equation of time. The earliest sunset in the Northern Hemisphere occurs in early December, about two weeks before the solstice. The latest sunrise occurs in early January, about two weeks after. This asymmetry is due to Earth's elliptical orbit.
Do sunrise/sunset times account for daylight saving time?
Yes. The times shown on city pages are in the city's local time, which includes any DST offset currently in effect. When clocks spring forward, sunrise appears one hour later on the clock (but the actual solar event is unchanged).
How accurate are the calculations?
The algorithm used is accurate to within 1–2 minutes for most locations. It does not account for local terrain (mountains can block the sun) or microclimate effects. For precise astronomical data, consult a dedicated almanac.