Cold, wet weather has made for a mild spring fire season for most of the West but also has created the threat of a blazing summer.

The El Nino phenomenon generated a swath of cooler, wetter weather running lengthwise across the center of the country and including California, Nevada, Utah, northern Colorado and southern Idaho and Wyoming. It minimized spring fires in these areas, said Janelle Smith, spokeswoman for the National Interagency Fire Center in Boise, Idaho.But, with forecasters seeing an end to El Nino, the stripe of green grasses could turn to brown tinder, boosting the fire danger in those states.

As of last week, a total of 661,694 acres had burned nationwide, down from the 10-year average of 835,702 by that date. But only 186,623 acres have burned in the western United States, with more than a third of that related to a single fire raging in Alaska.

Last year, the federal government spent $256 million nationwide fighting fires, again down considerably from the 10-year average of $412 million per year.

But like fire, the fire season is unpredictable.

"We're preparing for the season flip-flopping at a moment's notice," said Greg Zschaechner, manager of the Eastern Great Basin Coordination Center, which covers Utah, southern Idaho and portions of Wyoming. "We could be jumping into a fire season pretty quick because of all the fine fuels."

The fuel fire that most concerns officials is cheat grass, a fine grass that normally sprouts early in May, then quickly dries out, burning hot and fast when flames hit it.

"It's starting to dry out now, and when that happens anything could set it off," said Kathy Jo Pollock, spokeswoman for the Eastern Great Basin center in Salt Lake City.

To eliminate some of the fuel for summer fires, various agencies have burned 316,933 acres as a sort of pre-emptive strike. But sometimes even the supposedly controlled burns get out of control. Such was the case with a fire in southern Utah last week aimed at eliminating 800 acres of grass. It quickly spread to more than 3,000 acres.

"Because there is so much of that vegetation, if we do get that drying trend as we do in the summer, combined with thunderstorms . . . you get the potential for very flashy, quick-burning fires," Smith said.

Fighting such quick-moving grass fires presents different challenges from combating timber fires, which, although they can throw flames hundreds of feet high, generally move more slowly.

"Grass fires are more likely to trap people, because they can move as fast as the wind can blow," said Karen Terrill, spokeswoman for the California Department of Forestry and Fire Protection.