Frontier introduced the service — the first ever between the two cities — in May. The plan was to run the flights on a trial basis through Labor Day, but the Denver-based airline is extending them through Oct. 27, HIA said.

Flights to Denver leave Monday, Thursday and Saturday mornings, with return flights arriving on Wednesday, Friday and Sunday evenings. The route is served by 138-seat Airbus A319 aircraft.

Frontier also offers flights to Orlando. AirTran Airways, a subsidiary of Southwest Airlines Co., also flies that route but plans to discontinue it Aug. 12.