[did you know?] June 20 is Summer Solstice in the Northern Hemisphere, i.e. the longest day of the year. It's also called June Solstice.

The earth is currently at the leftmost position in the image above, when the upper part of its axis is tilted towards the sun. Image from Wikipedia.

June 20 is Summer Solstice (or "Midsummer") in the Northern Hemisphere, i.e. it is the longest day of the year. For example, in Amsterdam, the Netherlands, sunrise is at around 5:18am and sunset is at around 10:06pm - nearly 7 hours of sunshine!

It's also called June Solstice or Northern Solstice, because in the Southern Hemisphere it is technically Winter Solstice on June 20th.

To me, June 20 marks the start of the hot/warmer summer months in temperate climates (e.g. Tokyo, New York) in the Northern Hemisphere, just as 12:00pm (noon) marks the start of the hot/warmer afternoon of everyday. To me, June 20 also marks the start of rainy/typhoon season in the Philippines, although of course the rains already started pouring in May.