First official day of summer is on Sunday. Here's what happens during summer solstice
The summer solstice is known as the longest day of the year, as many cities such as Seattle will experience as much as 16.5 hours of daylight, while New York City and Boston will see 15.5 hours of sunlight.
Happy solstice! Thursday marks earliest summer solstice since George Washington's presidency
Astronomer Derrick Pitts, with The Franklin Institute, and FOX 9 Chief meteorologist Ian Leonard help FOX Weather ring in the summer solstice. This year's astronomical start to summer is the earliest since 1796.
With the final days of spring upon us and summer approaching, people look forward to the summer solstice, which marks the official astronomical start of the new season.
In an astronomical calendar, the seasons are defined by two solstices and two equinoxes, according to the NOAA.
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The planet’s tilt and the sun’s alignment over the equator determine both the solstices and equinoxes.
People have used this observable method for thousands of years.
"The equinoxes mark the times when the sun passes directly above the equator," experts at NOAA said.
"In the Northern Hemisphere, the summer solstice falls on or around June 21, the winter solstice on or around December 22, the vernal or spring equinox on or around March 21, and the autumnal equinox on or around September 22," they continued.
The elliptical shape of Earth’s orbit around the sun causes the lengths of the astronomical seasons to vary.
Cambridge, MA - 2/3/06 A jogger runs along the Charles River in Cambridge at sunset Friday. 020306featuredg - Staff Photo by David Goldman. Saved in Photo SATURDAY. (David Goldman/MediaNews Group/Boston Herald / Getty Images)
The two solstices are exact moments when the sun is in direct alignment with three specific bands of latitude.
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"The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India and southern China," the National Weather Service explained.
16 March 2025, North Rhine-Westphalia, Bonn: A walker is walking her dog through the Rheinaue. (Thomas Banneyer/picture alliance / Getty Images)
The Tropic of Cancer marks the most northerly latitude at which the sun can appear directly overhead at noon.
It is worth noting that meteorologists and climatologists consider June 1 the first day of summer, as opposed to people who prefer the astronomical calendar.
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Meteorologists break down the seasons by grouping them into three months based on the annual temperature cycle as well as the calendar.
YOSEMITE NATIONAL PARK, CALIFORNIA - JUNE 12: Visitors take a dip in Merced River in the heart of Yosemite Valley on June 12, 2026 in Yosemite National Park, California. The Merced River is a 145-mile river fed by snowmelt from the high Sierra Nevada and offers opportunities for swimming, rafting, and fishing. (Heather Diehl / Getty Images)
Dates and season lengths vary with astronomical seasons.
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The summer solstice is known as the longest day of the year, as many cities such as Seattle will experience as much as 16.5 hours of daylight, while New York City and Boston will see 15.5 hours of sunlight.
UTAH, UNITED STATES - 2025/10/18: People at the Canyonlands National Park overlook near the visitors center in Canyonlands National Park near Moab, Utah, United States. (Photo by Wolfgang Kaehler/LightRocket via Getty Images) (Wolfgang Kaehler/LightRocket / Getty Images)
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The summer solstice will begin on Sunday, June 21, at 4:24 a.m. EDT.