Hurry! These low fares are good only until 6 p.m.

JetBlue has just  tweeted this week's batch of its Cheeps — limited-time-only, super low fares that go crazy quick — and there are two opportunities for  travelers in the New York metro area.

New York to Tampa.  Saturday, Aug 20; returning Monday or Tuesday,  Aug. 22 or 23. For $99 each way

Newark to Boston. Saturday,  Aug. 20; returning Monday or Tuesday, Aug. 22 or 23. For  $39 each way.

Travel is valid only on Saturday, Aug. 20; and Monday or Tuesday, Aug 22 or 23. Seats are limited to 25  per flight, and the sale ends at 6 p.m.  Tuesday,  Aug. 9,  or earlier if seats run out.

To take advantage of these fares, flights must be booked on this page: http://www2.jetblue.com/deals/twitter/default.asp