How sunrise and sunset times work

There is no single sunrise or sunset time for today. The exact clock time depends on your latitude, longitude, date, and local time zone. Pick a location in the sunrise and sunset calendarfor today's dawn, sunrise, golden hour, sunset, and dusk, or open a coastal station calendar for a fourteen-day local forecast.

What sunrise and sunset actually mean

Sunrise is not the instant the center of the sun crosses a perfectly geometric horizon. The published time is the apparent moment when the sun's upper edge becomes visible. Standard calculations put the center of the sun about 0.833 degrees below the horizon to account for both the sun's apparent radius and the atmosphere bending its light. Sunset uses the same convention on the other side of the day.

That atmospheric correction is an estimate. Air pressure, temperature, and humidity change refraction near the horizon. A ridge, dune, skyline, or elevated viewpoint changes your visible horizon too. A calculated time is therefore the right planning reference, but the first or last visible sliver can differ at the exact place you stand. NOAA's solar calculation notes describe the standard refraction assumption and why uncertainty grows toward the poles.

Why the time changes every day

Earth's axis is tilted as the planet travels around the sun. That tilt changes the sun's apparent path across the sky through the year: longer and higher in summer, shorter and lower in winter. The daily change is fastest around the equinoxes and smallest near the solstices, when the seasonal trend turns around.

Earliest sunrise and latest sunset do not normally fall on the summer solstice. Clock time also reflects the changing speed of Earth in its orbit and the tilt between the equator and the sun's apparent path. Together those effects form the equation of time, the difference between uniform clock time and apparent solar time. That is why the year's earliest sunrise usually arrives before the longest day and the latest sunset arrives after it.

Why location matters, even inside one time zone

Latitude controls the seasonal swing. Near the equator, day length changes relatively little. Farther north or south, summer days stretch and winter days contract; above the polar circles the sun can remain above or below the horizon for an entire day.

Longitude controls where you sit within the time zone. Earth turns 15 degrees each hour, so a location on the eastern side of a zone reaches solar noon earlier by the clock than a location on the western side. Boston and Detroit can show very different sunrise times even while both clocks say Eastern Time. For a coast-specific answer, use the calendar attached to a real NOAA station—for example San Francisco sunrise and sunset or New York sunrise and sunset.

Time zones and daylight saving time

Astronomy changes smoothly; civil clocks do not. When daylight saving time begins or ends, the displayed sunrise and sunset times jump by an hour even though the sun's path barely changed from the day before. Reliable local calendars must apply the time-zone rules for the place and date—not just subtract a fixed offset from UTC. Perigee's local station calendars label times in the station's own time zone so a coastal plan does not inherit the browser's zone by accident.

Dawn, dusk, and the three twilights

Useful light begins before sunrise and continues after sunset. The terms describe how far the center of the sun is below the horizon:

• Civil twilight extends to 6 degrees below the horizon. Outdoor detail is often visible without artificial light.
• Nautical twilight extends from 6 to 12 degrees below. The horizon may still be distinguishable at sea.
• Astronomical twilight extends from 12 to 18 degrees below. Beyond it, the sky is considered fully dark for astronomy.

Dawn is the morning side of twilight; dusk is the evening side. Golden hour is a photographic label rather than one universal astronomical boundary, but it generally covers the warm, low-angle light shortly after sunrise and before sunset.

How daylight connects to a coastal plan

Sunrise does not change the astronomical tide, and sunset does not cause high water. They matter because the useful window for fishing, paddling, tidepooling, photography, and shoreline access depends on both water and light. A low tide that exposes a reef after dark is a different opportunity from the same low during civil daylight.

Start with the local sun calendar, then compare it with the tide chart for the same coast. The free Trip Health Check brings tide, wind, daylight, and source freshness into one planning view. It is a planning aid, not a navigation or safety forecast.

Sunrise and sunset questions

What time is sunrise today?

Sunrise depends on the date, latitude, longitude, and local time zone. Use a local calendar rather than a national time; even two cities in the same time zone can differ by many minutes.

Is dawn the same as sunrise?

No. Civil dawn begins while the sun is still below the horizon and usable natural light is growing. Sunrise is the later moment when the sun's upper edge appears at the horizon.

Why did sunrise move by an hour?

A sudden one-hour clock change is normally daylight saving time, not an astronomical jump. The solar event moves gradually, but the local clock label changes when the time-zone offset changes.

Why can observed sunrise differ from a calculated time?

Published times assume a standard horizon and atmospheric refraction. Terrain, buildings, elevation, pressure, temperature, haze, and clouds can change when you actually see the sun.