By Wendy Anders

Time to act if you want to nab some low fares on Southwest air which flies daily from several U.S. cities into the northern Liberia, Costa Rica airport or the San José capital airport.

A 21-day advance purchase is necessary, says the airline on their site, and these low fares are available for purchase only until January 26, 2017, 11:59 p.m. in the respective time zone of the originating city.

The low fares are available for international non-stop travel to Costa Rica’s two international airports, and also to Mexico, daily from January 24 through March 2, 2017, and March 29 through May 19, 2017, says Southwest.

On the airline’s list of announced low fares are Baltimore/Washington, D.C. – San José starting at $154 one-way.

Fares from Houston, TX to Liberia, Costa Rica are listed as starting at $145 one-way, and from Houston, TX to San José, Costa Rica starting at $143. From Los Angeles to Liberia, Costa Rica fares start at $174 one-way, says Southwest.

Please note that return flights have higher listed prices on the Southwest site.

Displayed prices include all U.S. and international government taxes and fees, added the airline.

Flights can be booked using the Southwest points system but these do not include taxes, fees, and other government/airport charges of at least $5.60 per one-way flight, said Southwest.

A whole host of low fares within the U.S. are also available under the terms listed on the Southwest site.