The 50-year average is 9.6 named storms, 5.9 hurricanes and 2.3 major hurricanes.
Researchers William Gray and Phil Klotzbach said in their extended-range forecast there is a 63 percent chance that at least one major hurricane will make landfall on the U.S. coastline.
The long-term average probability is 52 percent.
This is Gray's 26th year of forecasting hurricanes. His predictions are watched closely by emergency responders and others, but many say such long-range forecasts don't have a lot of practical value beyond focusing public attention on the dangers.
The hurricane season runs from June 1 to Nov. 30. Klotzbach cautioned that the December prediction includes "a large amount of uncertainty" because the season is so far in the future.
Last December, Gray and Klotzbach predicted 13 named storms for the 2008 season, including seven hurricanes, three of them major. In June they revised that to 15 named storms, eight hurricanes - four major. The season produced 16 named storms, eight hurricanes, with five major.
Klotzbach said the new forecast is based on factors including warm Atlantic sea surface temperatures and the likely absence of El Nino conditions.
El Nino is a warming in the Pacific Ocean that can have such far-reaching effects as changing wind patterns in the eastern Atlantic, which can disrupt the formation of hurricanes.
On the Net:
Colorado State University hurricane forecast: http://hurricane.atmos.colostate.edu