In general, when booking your flight to Europe, May is the cheapest month on average.
Most flyers found that booking flight tickets 55 days in advance of their planned departure date is, on average, the best time to get cheap flights to Europe.
From most locations, the cheapest flights to Europe are found on a Tuesday. Booking a Friday departure is usually the most expensive.
Typically, cheap prices to Europe are most often found for morning flights. Cheap prices are less likely for afternoon flights.