Revenue for May, which benefited from holidays to mark Labour Day, was us$3.7 billion, the second-strongest figure this year, according to government data released on Monday. Analysts had forecast a rise of between 12 and 15 % for May.
The monthly figures came after torrential rains and flooding hit Macau and nearby Guangdong province. The former Portuguese colony saw the heaviest rainfall since 1982 during the middle of May while transport access was restricted for close to two days.
Infrastructure developments in the coming years are expected to help lift the number of visitors to Macau. Currently most tourists come from Guangdong and other nearby provinces.
A bridge joining Hong Kong, Zhuhai and Macau is set to open by 2016 while expanded intercity rail links will help shorten the time of travel from China's northern cities to the gambling enclave.
Plans are also in place to upgrade Macau's capacity-constrained ferry terminals and international airport.