U.S. airlines will carry an all-time high number of passengers this spring, an industry trade group forecast on Wednesday, as increased competition and persistently lower fares make flying more accessible to the general public.

Airlines for America (A4A) said it expects carriers to fly 150.7 million passengers, 2.47 million per day, between March 1 and April 30, in a 4 percent increase from the year-ago period.

Despite a number of seasonal challenges, including a rash of late-winter storms, U.S. airlines are generally off to a successful start of 2018, with some carriers having raised their first-quarter outlooks in the last week based on better-than-expected performance.

"An expanding economy, employment gains and surging household net worth are also contributing to the growth in demand for air travel," A4A Chief Economist John Heimlich said in a statement.

The seasonal period includes several potential travel peaks, including U.S. college spring breaks, Easter and Passover.