The weather anomaly La Nina could influence global weather patterns through the early part of 2008, according to the National Weather Service.
The U.S. agency said La Nina conditions have developed across the equatorial Pacific Ocean during the past few months, though some forecasting models have predicted a more rapid development than has occurred.
La Nina, which means "little girl" in Spanish, is an unusual cooling of Pacific Ocean surface temperatures and can trigger widespread changes in weather around the world, including a higher-than-normal number of hurricanes in the Atlantic.
In its 90-day weather forecast, which runs from October to December, the agency predicted an increased chance of above normal temperatures in most of the United States, though not as high as last winter, which was exceptionally mild.
The only exceptions are along the Canadian border from Montana westward and in the Southeast along the South Atlantic Coast.
"Historically both of these regions experience near or below average temperatures associated with La Nina," the NWS said.
There is a greater chance of above normal temperatures in the Southwest due largely to long-term trends and ongoing drought conditions.
Most of the country will have an equal chance of precipitation, with the only exceptions being above-normal chances in the Northwest and below-normal chances in the Southwest.