One-day sale on Frontier to/from Denver, including Mexico

Frontier is having a one-day sale with good fares between various cities and Denver, including Cabo, Cozumel, Guadalajara, and Mazatlan. These fares can only be bought on Frontier's site. Purchase by April 18 (we're assuming  mountain time) and fly by June 13 Tuesday/Wednesday and noon to midnight on Saturday for domestic travel or Monday-Thursday for Mexico. A 10-day advance purchase is required.