CHICAGO, May 14 (Xinhua) -- Heavy thunderstorms caused hundreds of flight cancellations or delays on Monday morning at the Chicago O'hare International Airport, a busy air hub in the U.S. Midwest.

According to Flightradar 24, a global flight tracking service, as of 10:00 a.m. local time (1500 GMT), 73 percent of arrival flights were delayed with an average of 106 minutes, while 72 percent of departure flights being delayed with an average time of 44 minutes.

The flight tracker put the arrival delay index of O'hare at 5 and and departure delay index at 4.7.

The index ranges from 0 to 5, and the higher the number, the more serious situation it indicates.

Meanwhile, some 22 percent of outbound flights from O'hare were canceled, with 8 percent inbound flights being canceled due to bad weather condition.

Total canceled flights reached 193 in the past 24 hours, based on the data released by the Chicago Department of Aviation at 10:24 a.m. local time (1523 GMT).

The aviation authority also reported an estimated average delay time of 57 minutes in the next two hours.