Earth Sky News for June 12: Earliest sunrises before summer solstice

At mid-northern latitudes in the Northern Hemisphere, the earliest sunrises of the year happen around mid-June, despite the fact that the summer solstice – the year’s longest day – is still about a week away. And if you live at middle latitudes in the Southern Hemisphere, the earliest sunsets take place around now, even though the winter solstice – the year’s shortest day – isn’t for another week.

For those of you who are privileged enough to be outdoors before one of these early sunrises, you’ll find some of the most beautiful dawn twilights of the year.

The exact date of earliest sunrise varies with latitude. At 40^o north latitude – the latitude of, say, Philadelphia in Pennsylvania – the earliest sunrise of the year will happen on June 13. For that same latitude, the latest sunset of the year will fall on or near June 27. This is in spite of the fact that the longest day of the year (in terms of daylight) comes on the June summer solstice.

So it is for other Northern Hemisphere latitudes. The dates of earliest sunrise and latest sunset do not coincide exactly with the solstice. Appreciably south of Philadelphia’s latitude, the earliest sunrise has already come and gone (in late May or early June) and the latest sunset occurs at a later date (sometimes as late as July). In Hawaii, for instance, the earliest sunrise precedes the June solstice by about 2 weeks, and the latest sunset comes about 2 weeks after. Farther north, the earliest sunrise and latest sunset happen closer to the June solstice. Check it out at your latitude, using links on our almanac page.

The earliest sunrises come before the summer solstice because the day is more than 24 hours long at this time of the year. In the Southern Hemisphere, the earliest sunsets of the year come before the winter solstice for the same reason.

In June, the day (as measured by successive returns of the midday sun) is nearly 1/4 minute longer than 24 hours. Hence, the midday sun (solar noon) comes later by the clock on the June solstice than it does one week before. Therefore, the sunrise and sunset times also come later by the clock, as the tables below help to explain.

For Philadelphia (40^o north latitude)

Date	Sunrise	Midday (Solar Noon)	Sunset	Daylight Hours
June 13	5:31 a.m.	1:01 p.m.	8:30 p.m.	14h 59m 04s
June 20	5:32 a.m.	1:02 p.m.	8:33 p.m.	15h 00m 38s

For Valdivia, Chile (40^o south latitude)

Date	Sunrise	Midday (Solar Noon)	Sunset	Daylight Hours
June 13	9:12 a.m.	1:53 p.m.	6:34 p.m.	9h 22m 12s
June 20	9:14 a.m.	1:55 p.m.	6:35 p.m.	9h 20m 42s

Bottom line: The earliest sunrises of the year in either hemisphere always come before the summer solstice. The exact date of your earliest sunrise depends on your latitude, but the sequence is always the same: earliest sunrise, solstice, latest sunset.