Weather and the ability to be outside virtually year-round is one of Southern California tourism’s big selling points. In fact, the Anaheim Convention Center opened its 100,000-square-foot outdoor Grand Plaza last year just to take advantage of the weather.

So why would anybody want to build a new water park in Southern California with all the attractions indoors?

Kimberly Schaefer, chief executive of Wisconsin-based Great Wolf Resorts Inc., just points to last week’s heat wave.

“You do have weather,” she said. “Whether it’s too hot or the cool time or it rains, being indoors we have the opportunity to take the weather out of the equation.”

Schaefer, whose company has a dozen indoor water parks mostly in the Midwest, South and East Coast, is about to find out whether being indoors is an advantage in Southern California.

The company will break ground Wednesday on a new Great Wolf Lodge in Garden Grove that will feature a 121,000-square-foot indoor water park – the company’s largest – along with a 603-room hotel and conference center.

Besides being indoors, Great Wolf will be unusual in another way: Only hotel guests will be able to use the water park.

“It’s exclusive to resort guests,” said Susan Storey, spokeswoman for Great Wolf Lodge. “The lines are never crazy and you always have enough towels and lounge chairs.”

The $250 million development, which is scheduled to open in late 2015, has been years in the making, delayed by the recession and one of the worst downturns in tourism and hospitality history. But industry experts say the time is ripe for the project, as water parks, particularly indoor attractions, enjoy a major resurgence.

“The industry is definitely back,” said David J. Sangree, president of Hotel & Leisure Advisors.

He noted that there are now 834 water parks in the U.S., a 5 percent increase over 2013, and that development of indoor water parks, both in total numbers and size, is outpacing traditional outdoor facilities.

By Sangree’s count, 12 indoor U.S. water parks will be built this year compared to nine in 2013. Indoor water park construction will jump to 370,000 square feet this year, from 68,000 in 2013.