Aug. 3--The United States has nearly 22 percent more natural gas in storage now than the average for the past five years -- a stockpile that promises lower prices next winter.

That is, if hurricanes don't batter the Gulf Coast, if a summer heat wave does not return and if the winter temperatures are mild.

"It's those 'ifs' -- the uncertainty -- that's keeping the market supported at current prices," said E. Seth Wilson, an energy consultant.

Spot prices for natural gas have soared more than 30 percent in the past three weeks.

That surge reflects many doubts about whether the current stockpile will remain underground -- or will be burned as fuel -- before next winter.

It's no small question in the aftermath of the winter of 2005- 2006. Gulf Coast hurricanes disrupted natural gas supplies, sending prices to record levels -- and pushing home heating bills into uncharted territory.

The price of natural gas peaked Dec. 13 at more than $15.38 per million British thermal units (or 1,000 cubic feet) -- up more than $6 from the top price a year earlier. Prices plunged in the face of moderate heating demand in a mild winter. By January, February and March, prices ranged from a high of about $9 to a low near $6.

Few anticipate a return to such extreme price swings in the coming winter.

Indeed, until a few weeks ago, many analysts expected natural gas prices to be down 10 percent or more from last winter's average prices.

After all, a mild winter left a lot of natural gas in storage tanks, nearly 3.5 trillion cubic feet -- a record, but about 250 million cubic feet less than expected before July's coast-to-coast heat wave.

"I'm not sure it ever was a healthy surplus," said Severin Borenstein, director of the University of California Energy Institute.

Futures prices for gas to be sold next winter were high by historical standards as early as April, Borenstein said. Summer natural gas prices fell as inventories rose -- a buildup that paused with a surge in demand for natural gas needed to produce electricity in July.

Air conditioners may be driven by electricity, but many of the power generators erected in the past 10 years are fueled by natural gas.

"This summer is going to be a strain," Borenstein said of natural gas inventories.

Tim Carter, Xcel Energy Inc. director of gas supply, is more optimistic that natural gas prices will stabilize by next winter, but customers aren't likely to see any bargains.

"I was expecting prices to be similar to last year's November-to- March [costs]," Carter said. "I may have to adjust that thinking. [Average winter] prices probably will be higher than last year -- but not a huge increase." He declined to attach numbers to a forecast.

The U.S. Department of Energy forecast also expects moderation. "Natural gas prices are projected to be lower through the rest of this year relative to the corresponding period in 2005," the agency wrote in June.

The report anticipated a 2006 average of $7.61 per 1,000 cubic feet on the spot market, down $1.25 from the 2005 average. It forecast the average price would move back to about $8.13 next winter, when natural gas demand peaks. But the spot market already reached that price this month.

An updated agency forecast is expected next week.

Minnesotans, thanks to their proximity to Canadian natural gas pipelines, pay less than the national average because of lower transportation costs -- as much as $2 to $3 less than what Northeasterners pay per 1,000 cubic feet.

But Energy Department officials are quick to note that their forecasts assume no major disruptions in supply, among other things. Already, eyes are on Tropical Storm Chris, brewing off the Gulf Coast.

"We've got to get through August, September and October -- the key hurricane months -- unscathed to hope to have reasonable prices next winter," said energy consultant Wilson, a principal of Enmart Corp. in Riverside, Calif.

Summer temperatures represent another unknown.

"The hot weather is expected to continue," Wilson said. As a result, Wilson and other energy analysts expect natural gas prices to swing wildly for months to come.

"What you have now is such incredible volatility," said Michael Schick, president of Energy Analytics, a consulting firm in Houston.

"That's obviously going to continue in the weeks to come and, I think, all the way through the wintertime," he said.