This is a true statement.
The Alps are tall mountains, so they block the movement of air between the areas south and North to them. The areas south of the Alps are a lot warmer than the areas north of the Alps, and there is relatively littlie exchange of air between them.
So when one drives through the Alps (it's not too slow, as there are many tunnels!), one can change the climate very quickly - the reason why many people choose to go for holidays across the alps!