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Earliest sunrises before summer solstice

Top of post: June 2018 sunrise in Sea Bright, New Jersey, via Steve Scanlon Photography.

At mid-northern latitudes in the Northern Hemisphere, your 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, your earliest sunsets take place around now, even though the winter solstice – your shortest day – isn’t for another week.

For the Northern Hemisphere: Even if you’re not an early riser, this is a super month for a one-off early morning walk. The dawn light is beautiful at this time of year.

For the Southern Hemisphere: If you’re someone who relishes the day’s light, as many do, you’ll be glad to know the sunsets will soon be shifting later!

Early sunrise in Sweden via Per Ola Wiberg

Early sunrise in Sweden via Per Ola Wiberg.

The exact date of earliest sunrise (and earliest sunset) varies with latitude. At 40 degrees north latitude – the latitude of, say, Philadelphia in Pennsylvania – the earliest sunrise of the year will happen on June 14. For that same latitude, the latest sunset of the year will fall on or near June 27. Meanwhile, the longest day of the year – the day containing the greatest amount of daylight, overall – comes on the solstice on June 21.

So it is for other Northern Hemisphere latitudes. The dates of earliest sunrise and latest sunset don’t 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 two weeks, and the latest sunset comes about two 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.

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morning-sunrise-in-marsh-North-Carolina

View larger. | June sunrise over Currituck, North Carolina. Image via Greg Diesel Walck – Lunar/Landscape Photographer.

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 degrees north latitude)

 

Date Sunrise Midday (Solar Noon) Sunset Daylight Hours
June 14 5:31 a.m. 1:00 p.m. 8:31 p.m. 14h 59m 15s
June 21 5:32 a.m. 1:02 p.m. 8:32 p.m. 15h 00m 35s

 

 

For Valdivia, Chile (40 degrees south latitude)

 

Date Sunrise Midday (Solar Noon) Sunset Daylight Hours
June 14 8:12 a.m. 12:53 p.m. 5:34 p.m. 9h 21m 56s
June 21 8:14 a.m. 12:54 p.m. 5:35 p.m. 9h 20m 39s

 

Source: timeanddate.com

The primary reason for the earliest sunrise preceding the summer solstice (and the earliest sunset preceding the winter solstice) is the inclination of the Earth’s rotational axis. The earliest sunrise or sunset would take place before the solstice even if the Earth went around the sun in a circular orbit.

However, the Earth’s elliptical orbit does affect the severity of the phenomenon. At the June solstice, Earth in its orbit is rather close to aphelion – its farthest point from the sun – which lessens the effect. At the December solstice, Earth is rather close to perihelion – its closest point to the sun – which accentuates it.

At middle latitudes, the earliest sunrise/sunset comes about one week before the June summer/winter solstice, and the latest sunset/sunrise about one week after the June solstice.

Yet, at the other end of the year, at middle latitudes, the earliest sunset/sunrise comes about two weeks before the December winter/summer solstice, and the latest sunrise/sunset about two weeks after the December solstice.

Early sunrise by Flickr user Raffee

Early sunrise by Flickr user Rafa? Zi?ba.

Bottom line: Are you an early riser? If so – if you live in the Northern Hemisphere – you might know your earliest sunrises of the year are happening now. Southern Hemisphere? Your earliest sunsets are around now.

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Bruce McClure

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