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Latest Sunrise of Year not on Year's Shortest Day

The latest sunrise of the year follows the winter solstice, and the earliest sunset always precedes it. This is because the day as measured from true solar noon (Sun at highest point) to true solar noon exceeds 24 hours in length for several weeks before and after a solstice. The earliest noon of the year falls on or near November 3, with the Sun ahead of schedule by over 16 minutes. The Sun strikes noon at 11:44 a.m. local time. Over three months later, around February 11, the year's tardiest noonday Sun arrives more than 14 minutes late, climbing to its noontime high at 12:14 p.m.

At the equator, where the daylight hours remain equal throughout the year, the year's latest sunrise (and sunset) take place on the day on which the latest solar noon happens to fall. As you go farther north of the equator, the daily change in daylight hours becomes more manifest. Therefore, the closer you approach the Arctic Circle, the less the disparity between the dates of the winter solstice and the latest sunrise.

I provide three examples, my source being the US Naval Observatory. The date and time of the year's latest sunrises are highlighted in bold:

Honolulu, Hawaii
(21 degrees north latitude)

DateSunriseSolar NoonSunsetDaylight Hours
Dec. 217:04 a.m.12:30 p.m.5:55 p.m.10 hrs. 51 min.
Jan. 167:12 a.m.12:41 p.m.6:11 p.m.10 hrs. 59 min.
Feb. 117:04 a.m.12:46 p.m.6:27 p.m.11 hrs. 23 min.

Denver, Colorado
(40 degrees north latitude)

DateSunriseSolar NoonSunsetDaylight Hours
Dec. 217:17 a.m.11:58 a.m.4:39 p.m.9 hrs. 22 min.
Jan. 47:21 a.m.12:05 p.m.4:49 p.m.9 hrs. 28 min.
Feb. 116:58 a.m.12:14 p.m.5:31 p.m.10 hrs. 33 min.

Circle, Alaska
(65 degreees north latitude)

DateSunriseSolar NoonSunsetDaylight Hours
Dec. 2111:06 a.m.12:34 p.m.2:03 p.m.2 hrs. 54 min.
Dec. 2311:07 a.m.12:35 p.m.2:04 p.m.2 hrs. 54 min
Feb. 118:55 a.m.12:50 p.m.4:47 p.m.7 hrs. 52 min.

Final Note: Why not give Sunrise & Sunset Times to the Second?

As Steffen Thorsen's sunrise and sunset site explains, the vagaries of Earth's atmosphere make it impossible to predict sunrise and sunset times with absolute precision, especially at high latitudes north or south of the equator. Higher atmospheric pressure and lower temperatures increase atmospheric refraction, bringing about earlier sunrises and later sunsets.

copyright 2006 by Bruce McClure

December 2006 Feature * February 2007 Feature

Skywise "Latest Sunrise/Earliest Sunset" Comic Strip by Jay Ryan