As I've mentioned I usually use Google flights as my go to destination when initially planning any trip and as you can see there are multiple dates starting in August with extremely cheap fares. I randomly chose Frankfurt (FRA) as my destination but this sale seems to extend to almost anywhere in Europe.
I know it may be hard to see but for the same random dates I selected earlier to Frankfurt (FRA), I could easily go to Paris (CDG) for $647 round trip or Milan (MXP) for $661 round trip. And the list goes on and on for round trip tickets to these destinations: Dublin (DUB) for $579, Amsterdam (AMS) for $615, Prague (PRG) for $668, and Barcelona (BCN) for $641 just to name a few. And these rates are even cheaper if you are leaving from a larger international airport such as New York (JFK) or Washington DC (DCA).