Nine named storms formed in the Atlantic in the six-month hurricane season that ended Nov. 30 -- the fewest since 1997, when there were eight, and the first time in three years that no hurricane struck the U.S. mainland or the Caribbean region.
The number of storms fell within the range of the seven to 11 named storms forecasted by the National Oceanic and Atmospheric Administration and other weather groups in August.
The season was marked by a late start, when Tropical Storm Ana formed on Aug. 11.
The three hurricanes that developed were half the number in an average season, according to NOAA.
Of those, Hurricane Bill hit Newfoundland in August, Ida struck Honduras and Nicaragua in November, and Fred went nowhere in September.
Five storms swirled harmlessly in the open Atlantic. Tropical Storm Grace in September posed more of a threat to Ireland than to the U.S.
So what happened this year?
The El Nino factor
The calmer season was due to the El Nino factor, a cyclical Pacific Ocean warming phenomenon that creates atmospheric conditions hostile to hurricanes and prevents storms from strengthening, NOAA said.
Weather scientists say it is too early to tell if El Nino will still be active for the 2010 Atlantic basin hurricane season.
The first long-range seasonal predictions are due this month.