Six Flags Entertainment (SIX 0.70%) delivered better-than-expected quarterly results this morning, but you're not alone if you weren't paying attention. 

The fourth quarter is a seasonally sleepy period for the regional amusement park industry. Outside of October weekends for Halloween-themed haunt events, and a handful of warm-weather parks that are open year-round, the fourth quarter is pretty forgettable. Six Flags typically posts a loss for the period, generating less than 14% of its annual revenue. The real money is made during the second and third quarters, when spring-breakers and summer revelers hit the coasters.

However, Six Flags turned the unremarkable into the remarkable this morning. Revenue climbed a better-than-expected 7%, to $154.2 million, fueled by increases in what folks were willing to pay for admissions and what they spent once inside the park. Six Flags posted cash earnings per share of $0.15 a share, reversing a small shortfall during the prior year's holiday quarter.

This is naturally a great way for Six Flags to close out the year, and we'll get a better snapshot on the industry when peer Cedar Fair (FUN 0.42%) reports tomorrow. Analysts see Cedar Fair posting a small deficit for the quarter, and a small profit may no longer be much of a surprise after the strength at Six Flags. 

This is a good time to consider buying into the regional amusement park operators. Six Flags has wrapped up its fourth consecutive year of record results, and an improving economy should benefit the family-friendly thrill parks. 

Six Flags and Cedar Fair may not be as flashy as Disney and SeaWorld -- theme park operators with gated attractions that are generally open year-round -- but operating smaller local parks is still a sound business. 

The fourth quarter is more important at SeaWorld and Disney, but Disney has so many moving parts that a single quarter at its theme parks isn't going to move the needle. SeaWorld relies on the holiday quarter for nearly 19% of its annual revenue, but it's currently battling defecting bands and public scorn that accompanied the sleeper success of last year's Blackfish documentary that took SeaWorld to task for raising killer whales in captivity.

This brings us back to Six Flags and Cedar Fair as smart plays on improving discretionary incomes that should accompany an improving economy. Patient investors will also be rewarded along the way, because Six Flags and Cedar Fair command yields of 5% and 5.3%, respectively.

It's time to ride.