Duration of Daylight/Darkness Table for One Year: U.S. Cities and Towns

This data service provides a way for you to obtain a table of the duration of daylight or darkness for one year. This form is for U.S. cities and towns only.  For all other locations, in the U.S. or worldwide, specify the latitude and longitude using this form.

• Enter the year (1700 - 2100) for which the table is desired.
• Select the table type (daylight or darkness) from the pop-up list.
• Specify the location of interest using the fields provided on the form.
• Click the "Compute Table" 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.

Notes

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 file with over 22,000 places listed. 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.

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.

The local times used in these calculations are based on the standard time zone of the location.

For definitions of sunrise and sunset, see Rise, Set, and Twilight Definitions in our FAQ area.

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.

How to Print the Table

The table is 112 characters wide, so to print it you must use landscape orientation and 8-point (smallest) type. Consult your browser's documentation for details on how to change the font/text size. An alternative scheme is to save the table to a file on your computer (for example, in Internet Explorer, click on File then Save As...), then use your favorite word processor or text editor to print it.

How to Import the Table into a Spreadsheet

Open your favorite text editor, then copy the numerical part of the table (i.e., do not copy the table headings) from your browser and paste it into the text editor. Save the data as a text file.

In Excel 2003, click Data on the menu bar, then Import External Data, then Import Data. Select your saved text file. Choose fixed width in the dialog box. [In Excel 2004 for Mac, the commands are Data -> Get External Data -> Import Text File]

In Excel 2007, click Data on the menu bar, then From Text. Select your saved text file. Choose fixed width in the dialog box.