Atlantic hurricane activity may be suppressed this season by an El Nino event, according to the National Oceanic and Atmospheric Administration (NOAA).

The US Government agency forecasts a 50% chance of a below-normal season, a 40% chance of a near-normal one and only a 10% chance of an above-normal season.

The Atlantic hurricane region includes the North Atlantic Ocean, Caribbean Sea and Gulf of Mexico.

For the six months from June 1, NOAA predicts a 70% likelihood of eight to 13 named storms, of which three to six could become hurricanes.

Of those, one or two could develop into major hurricanes rated from Category 3-5.

El Nino causes stronger wind shear, which reduces the number and intensity of tropical storms and hurricanes in the region. It can also strengthen trade winds and increase atmospheric stability across the tropical Atlantic, making it more difficult for cloud systems leaving Africa to intensify into tropical storms.

“Even though we expect El Nino to suppress the number of storms this season it’s important to remember it takes only one landfalling storm to cause a disaster,” NOAA Administrator Kathryn Sullivan says.

NOAA forecasts a near-normal or above-normal season in the Central Pacific Basin and eastern Pacific.

Eastern Pacific tropical storms and hurricanes most often track westward over open water, sometimes reaching Hawaii.