It’s about to get a lot cheaper to ski at Jackson Hole Mountain Resort. Unless you have a lot of children, that is.

Jackson Hole Mountain Resort announced it will slash the August price of its all-mountain season pass to $1,255, a 25 percent reduction from last year’s price of $1,670. The price increases to $1,570 after August.

The new deal is called the Grand Pass and offers unlimited skiing for all 128 days of the season with no restrictions. It marks the lowest price for an all-mountain pass at the resort since the 1980s.

“We believe this will meet the needs of our local market,” resort President Jerry Blann said during a news conference Tuesday morning.

The resort’s new pricing plan comes as a value for some, but also features changes that will affect large families. Children ages six to 14 will now have to purchase a Junior Grand Pass for $149 to receive season-long lift access this year.

In previous years, the resort offer a Family First program, which allowed a free pass for children 14 and younger and 50 percent off the regular price for additional children in the family with the purchase of an adult pass.

The resort reported last summer that it issued more than 1,000 free children passes for the 2008-09 ski season.

High school students ages 15 to 18 can purchase a season pass for $275. Children 5 and younger still ski free. The Grand Pass also includes a complimentary START bus pass, a $125 value, plus Jackson Hole Ski Club membership and summer tram access.

Blann said the goal of the new pricing plan is to entice 10- and 20-day pass holders to purchase season passes.

“We understand that value and the freedom to ski anytime are the highest priorities for our guests,” Blann said. “The Grand Pass represents our biggest commitment ever to making unlimited skiing on this mountain as accessible as possible. This is a serious value proposition. We have not seen prices this low in well over two decades.”

The new program also allows families whose parents don’t ski a reasonable pass for their children. For a family with two school children, one 15 or older, the new price won’t be an additional burden, he said.

“It’s about even,” he said of what that family would pay last year compared with this year. “We think it still makes sense for the parents but also opens up an opportunity for kids” whose parents don’t ski.

The company will continue, unchanged, its school program that allows fifth- and sixth-graders to ski free on Wednesdays, with low-cost instruction and rentals.

To add further incentive for mountain users to buy a season pass, the resort also announced it was increasing prices on its weekend, 10-day and 20-day passes. The increases are moderate, between $50 and $100 more than last year.

A 20-day pass purchased in August will cost $1,015, a 10-day pass $595 and a weekend pass $790. These prices are valid from Aug. 2-30 and include a complimentary START bus pass. The resort sold 1,400 season passes last year and hopes to drive that number up this winter.

“I think we will see some of our 10- and 20-day people move up,” Blann said. “We’re counting on that. We might even see some people with second homes here buy season passes.”

Blann said there has been discussion at the resort for two years about restructuring pass prices.

“There’s been a lot of dialogue to get to this point,” he said. “We think it’s time to do this. With the capacity of our mountain, and the improvements over the years, it’s the right time to be able to do this.”

Jackson Hole was among the most expensive ski resorts in the United States last year. The new prices make the resort as affordable as comparable places.

Sun Valley’s season passes for this winter are on sale for $1,499 through July 31. Deer Valley is charging $1,630 for an early purchase season pass while a pass at Aspen, Colo., is going for $1,499.

Grand Targhee Resort is currently selling 2010-11 season passes for $599 until Sept. 12. The price increases to $799 after Nov. 2. Snow King sold its season passes for $225 last year and has not announced any changes for this season.

Jackson Hole Mountain Resort Chief Marketing Officer Chip Carey believes that if more season passes are sold, it will change the way people ski.

“The Grand Pass is a totally different experience,” he said in a statement. “It is Jackson Hole citizenship, with all of the accompanying benefits. Grand passholders need never miss a lap on a powder morning, and will find themselves coming out to catch the last few trams of the day.”

Season passes for seniors (ages 65 and over), will be $815 in August.