WASHINGTON (Reuters) - Winter will be warmer than normal in the U.S. Western and Plains states and colder than usual in the Southeast and mid-Atlantic regions, but the return of El Nino is making it hard for forecasters to hazard a guess for much of the country, meteorologists said on Wednesday.

The National Oceanic and Atmospheric Administration said in its winter weather forecast that the weather anomaly known as El Nino was making it difficult to predict whether the Northeast and Midwest would have colder, warmer or average winter temperatures.

"The odds are in favor of a winter similar to the last two," said Jim Laver, director of NOAA's Climate Prediction Center. "When it was all evened out it was a tale of two coasts, the average was cooler east of the Mississippi River, and west of the Rockies, it was on the warm side," he said.

Above average winter temperatures, along with drier conditions, were forecast for much of the West and the northern Great Plains, NOAA said, while cooler-than-normal temperatures, accompanied by more rain than usual, are expected in the U.S. Gulf Coast, Southeast and Mid-Atlantic regions.

With U.S. crude oil prices trading at record highs, a colder-than-normal winter could push energy prices even higher.

NOAA's forecast was released at the same time as the U.S. Energy Information Administration's winter energy outlook, which warned consumers that prices will rise for all major home heating fuels. Home heating oil, for example, will cost about 28 percent more than last year due to higher prices, the EIA said.

"I'd buy heating oil now or buy on any price decrease you see in the marketplace, which may or may not come," said Mark Routt, a senior analyst at Energy Security Analysis, who predicted prices would increase in November and December.

"Bottom line we're just going to have to get used to it, prices are going to be higher," he said.

EL NINO RETURNS

A weak-to-moderate El Nino will play a major factor in determining weather patterns in the United States through early 2005, NOAA said. If El Nino remains weak, the Northeast, in particular, should brace for a colder-than-normal winter, NOAA said.

El Nino, which is Spanish for "the little boy," is an abnormal warming of water in the Pacific Ocean every four to five years which can wreak havoc with global weather patterns.

"El Nino is going to play a large role in our winter weather," said Mike Halpert, head of forecast operations at the NOAA Climate Prediction Center.

El Nino last appeared from May 2002 through March 2003, causing record rains in Europe and Australia's worst drought in a century. In the United States, it aggravated drought in the Plains states and unleashed heavy storms in the South.

However, some pockets of the West such as parts of California and the extreme Southwest will get more rain than normal, NOAA said. That is welcome news for areas hit with several years of drought which has ravished crops, drained rivers and sparked fires in bone-dry forests.

Drought in the region should ease during the winter, but conditions have deteriorated so significantly in recent years that they are likely to persist for the long-term, NOAA said.

The government also forecast drier-than-average conditions this winter in the Midwest, northern Plains and Pacific Northwest.

NOAA's winter forecast is for December 2004 through February 2005. The agency is scheduled to issue an updated winter forecast on Oct. 21.