JetBlue Airways has scaled back its third-quarter capacity growth forecast by nearly half, citing severe summer weather and other operational disruptions that weighed on its performance.

The carrier said Thursday that available seat miles (ASM), a key measure of passenger capacity, are now expected to grow between 1.5% and 3.5% in the current quarter, a sharp reduction from its prior guidance of 3% to 6%. JetBlue Airways attributed the downgrade to operational chaos caused by adverse weather and air traffic control restrictions during July and August.

Across the U.S. aviation system, airports experienced extreme weather conditions on more than 40% of days compared with the average over the past three summers. Due to its heavy concentration in the Northeast, the airline saw flight cancellations related to air traffic control issues nearly double.

These disruptions have driven up unit costs, prompting JetBlue Airways to raise its third-quarter ex-fuel cost per ASM outlook to an increase of 6% to 8% year over year, up from its earlier projection of 2.5% to 4.5%.

Despite a host of unexpected headwinds, strong demand, a favorable fare environment, and the successful rollout of several commercial revenue initiatives by management have led JetBlue Airways to lift its revenue per ASM guidance. The company now anticipates unit revenue growth of 17% to 20% year over year this quarter, well above its prior range of 12.5% to 16.5%.

Fuel prices have also exceeded JetBlue Airways' earlier expectations. The average fuel price for the quarter is now forecast at $3.96 per gallon, compared with the previous estimate of $3.49 per gallon. In midday trading, JetBlue Airways shares were up 0.7%.