The sun and the clock in Potosí (2026)
Potosí lies at 65.8°W. Its time zone, UTC−4, is built around the 60°W meridian. The 5.8° gap between them means the clock runs roughly 23 minutes ahead of the sun: solar noon arrives at about 12:23 rather than 12:00. The zone holds UTC−4 all year — there is no daylight saving here.
The longest day of 2026 is 22 December, with 13h 19m of daylight. The shortest is 22 June, with 10h 57m. The swing between them is 2h 22m. Inside the tropics the day length stays within a narrow band all year.
The earliest sunrise and the latest sunset do not land on the longest day. In Potosí the sun comes up earliest on 27 November at 05:36, while the latest sunset waits until 18 January at 19:07. The equation of time is what separates them: the Earth's elliptical orbit and axial tilt move solar noon back and forth by several minutes over the year.
The sky stays usably light for a while after the sun goes down. In Potosí that civil twilight runs about 22 minutes at the equinox.
Every figure in this section is computed from the city's own latitude, longitude and IANA time zone using NOAA solar algorithms (Spencer, 1971), accurate to about ±2 arcminutes below 65° latitude.
