The arrival of June also heralds the first day of summer and thus, the Summer Solstice, the longest day of the year. Since the length of day/night varies with latitude (the more North you go, the more extreme the lighting), not all people will be having equal length nights on the longest day of the year. On the other hand, one thing is common for all Northern Hemisphere observers: the nights are sort, especially when considering that it the approximately 1 ½ hours after sunset and before sunrise aren't truly dark. Now the good news: the summer sky is a cosmic picture book.
By the time June arrives, some of the Spring constellations are already taking their annual dives out of view. Among these are Hydra, Cancer, and, to a lesser extent, Leo. By the arrival of June, the Big Dipper signpost is starting to become obsolete. As the Dipper begins its annual dive, on the other end of the arc,Corvus and Crater are already disappearing but Bootes and Virgo are coming into their best placements of the year. By the time July comes, you'll only be able to speed on to Spica under a truly dark sky. Besides the already mentioned herdsman and virgin, and crown, Hercules, the Summer Triangle (made up of constellations Lyra, Cygnus, and Aquila), Ophiuchus, and Serpens are all flying high at this time of year, too. For those who like to stay up later, Libra and Scorpius are also on the rise, as is deep sky treasure trove Sagittarius along with the ghostly arch across the sky that is the Milky Way. By the time the sky starts to brighten around 4:30am (sunrise is before 5:55 in mid month), a fall preview in the form of Pegasus, Andromeda, Aries, Capricorn, Aquarius, and even Pisces Australis is on tap, too.
On the planetary front, June marks a transition in that, for the first time in months, the majority of the planets are well-placed by the time the sky becomes dark which, this time of year, is rather late, but at least seeing the majority of planets won't involve staying up well past the arrival of true night. By the time it gets dark, Jupiter is in the Southwest and Mars, closely followed by Saturn, which comes to opposition on the 3rd, are in the Southeast. The good news is that three of the best planets to view with a telescope are near opposition this month, the bad news is that, thanks to the flattening ecliptic plane, their placement is less than ideal because viewing them requires looking through a lot of atmosphere which, in a telescope, can result in unsteady seeing at high power. Hint: dusk often offers a window of steady air good for planet viewing. Additionally, Mars's racing away from Saturn will slow until,come month's end, it becomes stationary as its retrograding period ends. Moving into the morning, Mercury will make a good for this time of year appearance mid-month. Venus? It's lost in the Sun's glare all of June but will be reappearing, albeit barely, come next month.