ST. LOUIS--DECEMBER 07, 2012-- Today, Frontier Airlines launched a nationwide fare sale from St. Louis and Kansas City -- dropping prices to the lowest we've seen for winter travel this year. This has set off a fare war, in which other major airlines are also now matching these prices.

These flights are available for travel January-early February and save as much as $150 on the usual cost of these routes. 

Roundtrip fares, including tax, from St. Louis include:

• Denver ... $109 (nonstop)
• San Diego ... $134
• Las Vegas ... $144
• Seattle ... $172 (nonstop)
• Phoenix ... $179

Roundtrip fares, including tax, from Kansas City include:

• Denver ... $109 (nonstop)
• Las Vegas ... $138
• San Diego ... $140
• Portland ... $144
• Fort Lauderdale ... $151
• Phoenix ... $172

The sale ends Monday, Dec. 10 at 11:59 p.m. EST. We anticipate that the other airlines will expire these fares by Monday night as well. Click below to search using Fly.com's Low Fare Calendars.