"It's all about fuel," Southwest spokeswoman Paula Berg wrote in an e-mail. "History proves that we give thoughtful consideration to fare moves. Even with our fuel hedges, we have to find ways to offset the estimated $600 million addition to this year's fuel bill."
Although experts say fares nationwide likely will rise at least 10 percent this year, Denver could continue to buck the trend as the city's major airlines expand and compete for customers.
Still, local consumers should consider booking tickets for summer travel soon, said Tom Parsons, who runs Texas-based travel site Bestfares.com. Prices always rise during the busy summer months, when overall demand balloons dramatically. While fares from Denver this summer might be lower than they were a year ago, they'll certainly be higher than they are right now, Parsons said.
"If you are a gambler and you don't care where you want to go, you could probably wait and find some good deals," Parsons said. "But if you're trying to go to a specific destination at a specific time, I'd strongly start considering buying before Memorial Day."
Why fares fell
* Eugene Dilbeck, executive director of the Center for Travel and Tourism at the University of Denver's Daniels College of Business:
"The presence of Southwest in the market, the fact that United is out of bankruptcy and Frontier's great success here are three components that have led to more competitive fares."
The airport posted an 8.3 percent increase in passengers in January compared with the same month last year.
The Air Travel Price Index is the latest evidence of how Southwest's entry into Denver has helped lower fares and spur more traffic.
Southwest Airlines' entry into Denver has boosted traffic, producing the so-called "Southwest effect."