John Wayne Airport saw passenger traffic fall 1.6% in November from a year earlier to 739,031.
The decline came from dips in both domestic and international travel, an airport spokeswoman said.
International traffic was off about 16% to 25,334, while domestic was down 1% to 713,697.
Southwest Airlines served the most passengers during the month (311,345). The total includes passengers served by Southwest subsidiary AirTran Airways.
United Airlines was the second busiest (131,322) followed by American Airlines (86,671).
Overall passenger traffic is still up 4% year-to-date to 8.44 million, with the airport on track to surpass last year’s total passengers served, the spokeswoman said.