Frontier Airlines will launch its first-ever nonstop flights to San Juan, Puerto Rico, from Philadelphia on June 11.

Introductory fares were available Tuesday for as low as $59 one-way to San Juan at

The San Juan flight on Airbus A321 aircraft will operate daily, year-round except for two months in the fall -- after Labor Day until mid November -- "when travel demand naturally falls off," said Frontier vice president Josh Flyr, who joined Philadelphia airport CEO Chellie Cameron at PHL for the announcement.

"The flight will be back in mid-November, and then will operate continuously up until Labor Day of next year, so it's a brief seasonal hiatus when demand falls off," Flyr said.

San Juan will be Frontier's 18th destination from Philadelphia this summer. The flight will depart PHL at 9:15 p.m., arriving in San Juan at 1:23 a.m. The return flight will leave San Juan at 2:25 a.m., and arrive in Philadelphia at 6:43 a.m.

The $59 deal is available for travel on Tuesdays and Wednesdays, June 13 through Aug. 9, with blackout dates July 4 and July 5. Fares must be purchased by 11:59 p.m. on March 29. Seats are limited at the introductory fare rate, and certain flights and/or days of travel may be unavailable, the airline said.

While base fares are lower, Frontier charges extra for a carry-on bag in the overhead bin, advance seat assignments, and even a soft drink on the airplane. Passengers can pay for packages called "the works" and "the perks" that include a carry-on or checked bag, seat selection, priority boarding, a refundable ticket, and the ability to change a flight without a change fee.

"We are very excited that Frontier will be offering nonstop service from Philadelphia to San Juan, which is a popular destination for both tourists and natives of Puerto Rico who travel back home to visit," Cameron said.

"Philadelphia is a great success story for Frontier Airlines," said Flyr. PHL will be the fourth-largest airport station in the Frontier network this summer after Denver, Orlando, and Las Vegas, he said.

Frontier has been expanding its "low fares done right" strategy that offers "flexible, affordable, and family-friendly travel options for people who, quite frankly, in a lot of cases have been priced out of the airline market," Flyr said.

Frontier also flies from Trenton-Mercer Airport in Ewing Township, N.J.