You're right, I've heard that the Milky Way is more visible in the summer but do you know why that is? It would seem to me that since we're in it, it should be visible year round as long as it's dark enough.
I should have been more precise: I meant the
core of the Milky Way, its brightest part.
First of all, the position of the Milky Way in the sky and the night sky itself is different whether you're in the Northern or Southern Hemisphere. For example the Magellanic Clouds are only visible from the Southern Hemisphere (that's a shame!

).
See it that way: the Earth being on one side of the Milky Way you have the core of the galaxy on one side and the "suburbs" on another side.
As time goes by, the Earth rotates around the Sun. So we're not on the same side in the winter or in the summer.
When it's night in the summer (Northern Hemisphere), we are on the wrong side of the Sun to see the core of Milky Way. During the summer, the Earth is on the other side of the Sun, and therefore when it's night, we are on the "right (as in
good) side" of the Sun and we can see the core of the Milky Way.
Here's a simple way to explain it :
(
Source)
Hope it helps!