China's civil aviation watchdog is stepping up efforts to keep airlines on schedule amid a midsummer travel peak that coincides with frequent extreme weather, including storms and heavy rain.

"Chinese flights' on-time performance hit 80.35 percent during the first half this year," a year-on-year improvement of 0.83 percentage points, Sun Shaohua, deputy head of the Civil Aviation Administration of China's operations and monitoring center, told a news conference on Tuesday.

The country handled over 2.92 million flights in the first six months of the year, up 7.03 percent year-on-year. Sun said flight punctuality improved steadily despite the increase in flights.

However, more delays due to extreme weather are expected from July to August, the peak summer travel season, which will pose a challenge to punctuality, CAAC said.

"The Yangtze River region and Pearl River Delta region, for example, will see rain for half the season. And the airport in Guangzhou will also experience over 40 days of thunderstorms," said Yu Biao, deputy director of CAAC's transport department, adding that at least seven typhoons are expected to hit airports in coastal parts of eastern and southern China.

Domestic airlines have grounded all their Boeing 737 MAX 8 jets due to serious safety concerns following two crashes. With demand for air travel still increasing, the unexpected decrease in the availability of planes will have a negative impact on flight schedules, Yu said.

Although airlines have been maximizing use of their other planes to make up for the shortfall, air transport capacity to some popular summer destinations is unlikely to be able to meet demand, he said.

To provide a better travel experience for passengers during the wet season, CAAC is requiring airports, air traffic control facilities and airlines to evaluate and analyze major delays, identify the causes and fix problems in a timely manner.

Airlines are being encouraged to fly around extreme weather events to minimize delays, and civil air traffic control departments have been told to coordinate with military air traffic controllers to free up more flight paths for commercial flights.

The number of flights this summer is expected to be about 7 percent higher than the same time last year. Daily flight volume hit a record high of 17,435 on June 3, CAAC said.