Duration of Daylight/Darkness Table for One Year

This data services provides a method for obtaining a table of the duration of daylight or darkness for any year between 1700 and 2100.

Use the following steps to create a table for any location worldwide:

Enter the year (1700 - 2100) for which the table is desired.
Select the table type (daylight or darkness) from the drop-down list.
Specify the location of interest using the fields provided on the form. Use the buttons to find coordinates of cities or towns in the U.S. or its territories, or to convert between Degrees-Minutes-Seconds (DMS) and Decimal Degrees.
Click the "Get Data" button at the end of the form to compute the table. The table will provide the data requested in hours:minutes format.

Be sure to read the Notes section for an explanation of the items in the table.

US Location For example: Washington, DC

City

State or Territory

The place name you enter above must be a city or town in the U.S. The place's location will be retrieved from a list of over 22,000 places. Either upper- or lower-case letters or a combination can be used. Spell out place name prefixes, as in "East Orange", "Fort Lauderdale", "Mount Vernon", etc. The only exception is "St.", which is entered as an abbreviation with a period, as in "St. Louis". You need only enter as many characters as will unambiguously identify the place.

Specify year, type of table, and place:

Year For example: 1986

Type of table

Location Coordinates in decimal degrees, North and East are positive. For example: 38.9072, -77.0369

Latitude

Longitude

Location Label Custom label for printed output. For example: Washington, DC

Need coordinates? Try NGA's GEOnet Names Server (GNS)
Need U.S. coordinates? Try the USGS Geographic Names Information System (GNIS) .

Time Zone Example: 5 hours West of Greenwich (UTC-5) is Eastern Standard Time

hours

direction

East of Greenwich (UTC)

West of Greenwich (UTC)

Need a time zone? Try the time zone map.

Notes

Explanation

The Duration of Daylight table provides, for each calendar date, the total time that any portion of the Sun is above the horizon. Typically (for low and mid-latitude locations), this will be the elapsed time beginning at sunrise and ending at sunset.

The Duration of Darkness table provides, for each calendar date, the total time that the entire Sun is below the horizon. Typically (for low and mid-latitude locations), this will be the sum of two elapsed times: the time beginning at local midnight and ending at sunrise, and the time beginning at sunset and ending at local midnight.

For definitions of sunrise and sunset, see Rise, Set, and Twilight Definitions in our Astronomical Information Center.

For an explanation of why there is generally more daylight than darkness during the equinoxes (and all year at the equator), see Length of Day and Night at the Equinoxes and Comparative Lengths of Days and Nights.

High Latitude Remark

The returned table gives the duration of daylight or darkness on each calendar day. Sometimes at high latitude locations the duration of daylight depends on the longitude and time zone specified. Anomalous atmospheric refraction effects, which are not uncommon occurrences at high latitudes, may also significantly alter the time of sunrise and sunset, resulting in large differences from the durations of daylight and darkness that are calculated here.

Time Zones

When using the "Need USA Location" button, the service will fill the Time Zone hours field and set the Time Zone direction button according to the current standard time zone of the US place entered.

The railroads introduced standardized time zones to the USA in 1883. Since then, time zone boundaries have evolved considerably, with many cities and counties shifting from one zone to another. This service makes no attempt to track such historical changes.

For locations that require it, you may enter the time zone in decimal hours. For example, for locations in India, you may enter 5.5 hours east of Greenwich for the time zone. The time zone field can accommodate up to five characters.