Frontier adding 18 nonstop routes, including new flights to Caribbean, El Salvador and Guatemala

Dawn Gilbertson | USA TODAY

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Frontier Airlines, the no-frills carrier with cheap tickets and a pile of fees, is growing again.

The Denver-based airline on Wednesday announced 18 new nonstop routes and put seven previously announced routes out of Newark International Airport, which it began serving in November after Southwest Airlines' exit, on sale.

The new flights include Frontier's first service to El Salvador and Guatemala, and a big boost in flights out of Miami, a hub for American Airlines. Frontier has served Central America in the past, but with service to Costa Rica that has since ended.

The airline is also adding two new destinations in the Dominican Republic: Santo Domingo and Santiago. Frontier already serves Punta Cana and was supposed to add Newark-Punta Cana next spring, but tickets did not go on sale today along with other new Newark routes, and the airline provided no details on the flights.

Frontier regularly experiments with routes, introducing most on a seasonal basis with flights a few times a week, and quickly pulls them if bookings don't meet expectations.

Like fellow discounters Spirit and Allegiant, Frontier charges for carry-on bags and soft drinks on the plane, in addition to the typical airline charges for checked bags.

Frontier Airlines' new flights

Miami International Airport to and from:

Austin, Texas : Flights will be offered three times a week beginning April 23, with one-way fares starting at $49.

: Flights will be offered three times a week beginning April 23, with one-way fares starting at $49. Baltimore/Washington International Airport : Daily flights begin April 23, with one-way fares starting at $39.

: Daily flights begin April 23, with one-way fares starting at $39. El Salvador International Airport: Flights will be offered three times a week beginning June 18, with one-way fares starting at $59.

Flights will be offered three times a week beginning June 18, with one-way fares starting at $59. Guatemala City La Aurora International Airport : Daily flights begin May 10, with one-way fares starting at $59.

: Daily flights begin May 10, with one-way fares starting at $59. Long Island (New York) MacArthur Airport : Daily flights begin May 10, with one-way fares starting at $49.

: Daily flights begin May 10, with one-way fares starting at $49. Ontario International Airport, California : Daily flights begin April 23 with one-way fares starting at $69.

: Daily flights begin April 23 with one-way fares starting at $69. Santo Domingo Airport, Costa Rica : Daily flights begin April 23, with one-way fares starting at $89.

: Daily flights begin April 23, with one-way fares starting at $89. Trenton-Mercer Airport, New Jersey: Flights will be offered three times a week beginning April 23, with one-way fares starting at $49.

Baltimore/Washington International Airport to and from:

El Salvador International Airport : Daily service begins June 18, with one-way fares starting at $79.

: Daily service begins June 18, with one-way fares starting at $79. San Juan, Puerto Rico: Daily service begins April 23, with one-way fares starting at $69.

Newark, New Jersey to and from:

Santo Domingo, Dominican Republic: Daily service begins March 10, with one-way fares from $89.

Daily service begins March 10, with one-way fares from $89. Santiago, Dominican Republic: Daily service begins May 28, with one way fares from $89.

Ontario International Airport, Ontario, California, to and from:

El Salvador : Flights will be offered three times a week beginning June 18, with one-way flights starting at $89.

: Flights will be offered three times a week beginning June 18, with one-way flights starting at $89. Las Vegas : Daily service begins April 23, with one-way fares starting at $29.

: Daily service begins April 23, with one-way fares starting at $29. Guatemala: Daily service begins May 10, with one-way fares starting at $89.

San Juan, Puerto Rico, to and from: