Frontier Airlines will start Philadelphia and Orlando routes to San Juan, Puerto Rico on June 11, with fares that will cut current roundtrip prices in half in many cases.

Here’s what Google’s roundtrip fare calendar looks like when Frontier enters the market in Philly:

Here’s what it looks like for Orlando, where Frontier will unseat Spirit as the cheapest option for getting to Puerto Rico:

To make sure this wasn’t just a normal seasonal fare fluctuation, I checked Miami’s fares to San Juan, and they seem to go up in June:

For people who have a hoard of Frontier miles they don’t know what to do with, these routes could be a great way to use up those miles.

Frontier is charging its domestic minimum roundtrip price of 20k miles on these routes, instead of the international route minimum of 30k miles.

For Philly folks, this could be an opportunity to make the impossible possible: getting more than a penny per mile of value out of Frontier miles (if a $100 flight costs 10k miles, that’s exactly one penny per mile).

Here is the fare calendar for Philly in June:

And here is the same calendar in miles:

For both Orlando and Philly, roundtrip award flights to San Juan are available on plenty of dates at the 10k-mile minimum rate.

As a side note, the Philly route has bizarre departure/arrival times:

Does a 2am to 7am flight cut down the costs for Frontier maybe? (If anyone knows, please comment below.)

In other news, Frontier just filed to be the first U.S. airline since Virgin America to go public and have an Initial Public Offering (stock market launch).

Here’s my review of the Frontier Airlines credit card, which has a sign-up bonus of 40k miles.