This price is available for flights departing on Fridays, and returning on Sundays, on a couple weekends in early February. Longer weekends and other days of the week are also available for this price during the winter months.
You'll find similar fares on American, Delta, and Spirit from New York-Laguardia (LGA) to Dallas-Ft. Worth (DFW), but those airlines have Basic Economy restrictions. Southwest includes a normal carry-on bag, two free checked bags, and has no change fees. Plus, you'll be able to fly into the smaller Love Field Airport in Dallas (DAL). For more of Southwest's perks, read How to Fly Southwest (And Get the Seat You Want).
I found seats on Southwest departing New York LGA on Friday, February 1, returning from Dallas DAL on Sunday, February 3.
Need a room in Dallas? Here's what's available for the mentioned weekend dates on Hotelwatchdog.