The trading frenzy came following last Friday's warning from the National Weather Service that August will be hotter than usual, and that most of the nation will suffer more "extreme heat" all month. 

A stifling heatwave two weeks ago killed 100 people in California; about one dozen in Missouri, and also blacked out Queens for 10 days. 

New heat warnings are in effect from New York to Chicago, and points south. Yesterday, St. Louis, Mo. hit 103. 

In Chicago, a utility shut down one of the area's two nuclear reactors because the lake waters used to cool the reactors was too warm to use. 

Another event triggering the high prices was the surprise withdrawal of 7 billion cubic feet of natural gas last week from underground storage tanks. Supplies typically build during summer. 

The surge comes just as traders prepare for their big winter buying bets, which usually push gas futures up by as much as 30 percent. 

Last winter, natural gas hit $15.50 as a result of hurricane shortages. Unlike last year, however, storage tanks have more supplies, which could hold down natural gas prices for winter months. 

Futures for December are settling at around $10.20 per 1,000 cubic feet.  

The country's natural gas inventory is well above historical levels at 2.76 trillion cubic feet, says the Energy Department. The five-year average for this time of year is 2.27 trillion cubic feet. 

Unless a hurricane knocks out gas production, natural gas prices will drop back to lower levels by September, said energy analyst Dan Lippe of Petral Worldwide. 

"You will see storage facilities full well before the last week of October," Lippe said.