The fugure represents a rise of 6% or 1.2 million passengers on the same period a year ago.
Almost 3.1 million passengers used the airport in August – the second consecutive month that Dublin Airport has welcomed more than three million passengers.
Passenger numbers increased by 7% last month, making it the busiest August in the airport’s 77-year history.
Passenger volumes to and from continental Europe increased by 7% with more than 1.6 million passengers travelling to European destinations during the month.
The number of passengers travelling to UK destinations in August was flat compared to last year, with just over 922,000 passengers taking flights to and from the UK last month.
More than 409,000 passengers travelled to North America in August, a 21% increase compared to last year.
Traffic to other international destinations, which includes flights to the Middle East and Africa, increased by 14%, as 95,000 passengers travelled on these routes during August.
Passenger numbers on domestic routes declined by 1% with 10,000 travelling on domestic flights last month.
The number of passengers using Dublin Airport as a hub to connect to another destination increased by 42% in the first eight months of the year, with more than one million passengers transferring at Dublin so far this year.