Port Aransas Sunset Calculator

How the calculator works (the exact math)

These times are not guesses or scraped from another site — they are computed from the standard NOAA solar-position equations for Port Aransas's coordinates (27.8339° N, 97.0611° W). The same algorithm powers government and almanac sunrise/sunset tables, and the results here match them to within about a minute.

The chain of the calculation is:

1. Julian day — the calendar date is converted to a continuous day count so the sun's position can be found precisely.
2. Solar declination (δ) — how far north or south of the equator the sun is that day (about +23.4° at the June solstice, −23.4° in December).
3. Equation of time — a correction (up to ~16 minutes) for the Earth's tilted, elliptical orbit, which is why solar noon drifts off clock noon through the year.
4. Hour angle (H) — solved from cos H = (cos 90.833° − sin φ · sin δ) / (cos φ · cos δ), where φ is the latitude and 90.833° is the sun's zenith angle at sunrise/sunset (it bakes in atmospheric refraction and the sun's upper edge).
5. Sunrise / sunset — solar noon minus the hour angle gives sunrise; solar noon plus it gives sunset. The UTC result is then shown in America/Chicago time, with daylight saving applied by the browser's own timezone data.

Worked example. On the June solstice, the sun's declination is near its maximum, the hour angle is large, and Port Aransas gets its longest day — sunrise about 6:32 AM and sunset about 8:26 PM CDT, roughly a 13-hour, 54-minute day. Six months later, at the December solstice, the declination flips negative, the hour angle shrinks, and the day collapses to about 10 hours 23 minutes (sunrise near 7:14 AM, sunset near 5:37 PM CST).

Month-by-month reference table

Typical sunrise and sunset for the 15th of each month in 2026, so you can plan without opening the tool. Day-to-day change within a month is only a minute or two, and year-to-year change is under a minute.

How to read your result

• Planning a sunset photo or dinner? Aim to be in position at the golden hour start shown above — usually 30 to 40 minutes before sunset. That warm, low-angle light is the good stuff, and the bay-side spots fill up.
• Want the sun over the water? Port A's Gulf beach faces east, so plan sunset viewing on the bay (west) side of the island. The Gulf beach is for sunrise.
• Staying out after sunset? The listed blue-hour end is roughly when it gets too dark to shoot or safely wade — head in by then.
• Fishing the light? Sunrise and sunset are the classic low-light windows; use the exact times to be set up before first or last light rather than chasing it.

Assumptions and limits

• Times are for Port Aransas's coordinates. Elsewhere on Mustang or North Padre Island they shift by only seconds, but far inland cities differ by minutes.
• The math assumes a flat sea horizon and standard atmospheric refraction. Dunes, buildings, tree lines, or heavy haze will make the sun visually disappear a few minutes before the computed sunset.
• Refraction varies slightly with temperature and pressure, so treat the result as accurate to about a minute, not to the second.
• This tool reports sun position only. It does not predict clouds, fog, or whether the sky will actually color up — check the forecast for that.

Frequently asked questions