Liverpool John Lennon airport handled 517,000 passengers last month – the highest monthly figure since August 2011.
The 3% year-on-year growth contributed to more than 70,000 extra passengers using the airport so far this year.
The busy August helped boost total passenger numbers for the year to date to almost 3.4 million.
New routes started by Blue Air to Alicante, Milan, Larnaca and Rome; Ryanair to Prague, Bari and Girona; Wizz Air to Lublin and Tui to Ibiza helped push up numbers.
New routes are planned later in the year to Venice and Milan by easyJet and Ryanair respectively.
Super Break is starting a charter service to Iceland, while Transun and Santa’s Lapland are offering increased Lapland charters later this year.
Air service development director Paul Winfield said: ”We are delighted to see continued growth at Liverpool John Lennon airport and continue to work with existing and new operators to explore further opportunities from here.”