LGBTQ+

Here in Germany they tend to be clustered around the anniversary of the stonewall riot (28.06.) and named after the street it took place one (Christopher Street Day). But maybe some other occasion would have established it self, if stonewall happened in winter

I'm pretty sure it's because there's a massive student population and the last half of June is right around the end of the spring semester when people are either studying for exams or going home. That being said, I'm pretty sure winter exams are either now or starting soon.

Pride is usually in June because that's when Stonewall took place. Coincidentally, in the US, that's also the month in which same sex relationships were legalized (2003), same sex marriage was legalized (2015), and lgbtq people received the right to hold a job (2020).

That said, some cities will hold their pride celebrations at different times either because of a local event involving the lgbtq population or because they want to boost their numbers by having pride when big cities aren't.