In general when looking for the cheapest flight to Zagreb, try to book your flight during the month of November for the best deal.
On average, from most locations, when planning your trip to Zagreb, try to book your flight in the region of 16 days in advance for the cheapest prices.
From most locations, the cheapest flights to Zagreb are found on a Monday. Booking a Wednesday departure is usually the most expensive.
Typically, cheap prices to Zagreb are most often found for evening flights. Cheap prices are less likely for midday flights.