On May 31, at the outset of hurricane season, Gray had called for 17 named storms and nine hurricanes, five of them intense.
"We've lowered our forecast from our May predictions because of slightly less favorable conditions in the tropical Atlantic," said Philip Klotzbach, a member of Gray's team at Colorado State University.
The new forecast calls for three named storms, two hurricanes and one intense hurricane in August; five named storms, four hurricanes and two intense hurricanes in September; and five named storms, two hurricanes and one intense hurricane in October and November combined.
The Atlantic hurricane season, which runs from June 1 to Nov. 30, averages 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes per year.
Despite the reduction, Gray said, the activity called for in the new forecast is still 60 percent more than the long-term average.
There were 10 named Atlantic storms last year and five hurricanes, two of them major. None of the hurricanes hit the U.S. coast.
The latest forecast put the chances of an intense hurricane hitting the U.S. coastline at 68 percent for the rest of this season.
Chances of an intense hurricane hitting the East Coast, including the Florida Peninsula, are 43 percent, Gray said. For the Gulf Coast from the Florida Panhandle to Brownsville, Texas, the probability is 44 percent.
The forecast also called for above-average risk of a major hurricane making landfall in the Caribbean.
The devastating 2005 season set a record with 28 named storms, 15 of them hurricanes. Four hurricanes hit the U.S., including Katrina, which devastated parts of the Gulf Coast.