Due the leap year the summer solstice happens one day earlier.
The summer solstice is perhaps the most widely recognized day upon which summer begins.

It has been universal among humans to treasure this time of warmth and light.
For us in the modern world, the solstice is a time to recall the reverence and understanding that early people had for the sky. Some 5,000 years ago, people placed huge stones in a circle on a broad plain in what’s now England and aligned them with the June solstice sunrise. Around the same time Stonehenge was being constructed in England, two great pyramids and then the Sphinx were built on Egyptian sands. If you stood at the Sphinx on the summer solstice and gazed toward the two pyramids, you’d see the sun set exactly between them.