An “active” US hurricane season is increasingly likely as warm Atlantic Ocean temperatures raise the risks, according to forecasts issued as the peak storm period arrives.

The National Oceanic and Atmospheric Administration (NOAA) says there is a 60% chance of an above-normal season, up from its May prediction of 45%. Forecasts indicate 2-5 hurricanes of at least Category 3 strength, 5-9 hurricanes in total and 14-19 named storms.

The Atlantic hurricane season runs from June to the end of November, and peaks from August to October. Because major US population centres are potentially exposed to hurricane activity, the hurricane season can influence global reinsurance and coastal US insurance rates.

“Wind and air patterns in the area of the tropical Atlantic and Caribbean, where many storms develop, are very conducive to an above-normal season,” Climate Prediction Centre hurricane forecaster Gerry Bell says. “This is in part because the chance of an El Nino forming, which tends to prevent storms from strengthening, has dropped significantly from May.”

NOAA says tropical Atlantic temperatures are warmer than models previously predicted.

Colorado State University forecasters Philip Klotzbach and Michael Bell anticipate eight hurricanes, unchanged from their forecast last month, and expect 16 named storms compared with the previous outlook for 15.

For the entire US coastline, there is a 62% chance of at least one hurricane with Category 3-5 strength making landfall, compared with the 52% season average for the past century.

“Most of the tropical and sub-tropical Atlantic is anomalously warm and is likely to remain so,” the forecasters say.