Washington (CNN) -- The top U.S. airlines earned a net profit of $3.8 billion during the first half of this year -- up from $1.6 billion during the same period last year, according to an industry group.
The airlines were assisted by a 2.3% decline in jet fuel prices and modest declines in maintenance expenses and aircraft rents, according to the group, Airlines for America.
And the jump came despite numerous extreme weather events that interrupted travel earlier this year, including the polar vortex and severe thunderstorms.
The $3.8 billion was the combined profit for the six-month period for the nine major passenger airlines -- Alaska, Allegiant, American, Delta, Hawaiian, JetBlue, Southwest, Spirit and United. The 5% net margin, or five cents on every dollar of revenue, was an improvement from the 2.1% margin reported in the first half of 2013.
The industry group said that the nine airlines spent $7 billion to buy and refurbish aircraft and were able to reduce gross debt by $1.8 billion during the period.
The group also predicted Labor Day travel would increase 2% over last year's holiday, which is measured over seven days. Airlines for America expects 14 million air travelers, compared to 13.8 million in 2013. The busiest day will likely be Friday, August 29, the group predicted.