The US faces one of its "more active hurricane seasons on record", and a growing likelihood of a La Nina weather pattern, which often spells a crop-damaging heatwave, official forecasts have warned.

The Atlantic hurricane season, which typically peaks in August, could produce up to 23 named storms and seven major hurricanes – compared with an average of two – America's National Oceanic and Atmospheric Administration said.

That would put this season nor far behind 2005's, the most active so far, which witnessed 28 major storms, of which seven developing into major hurricanes, and caused an estimated $130bn of damages and costing more than 3,000 lives.

It also caused major damage to the citrus crop in Florida, America's biggest orange-producing state, which extended long term through the time needed to develop groves and the spread of diseases, such as citrus canker, fostered by the storms.

"This season could be one of the more active on record," Jane Lubchenco, the NOAA administrator, said.

"We urged everyone to be prepared."

'Drought risk is real'

The NOAA also warned of a growing risk of La Nina, a weather pattern linked to Pacific conditions which often cause hot and dry weather in America's main crop growing regions, besides being an indicator of a greater hurricane risk.

"Conditions in the equatorial Pacific Ocean are becoming increasingly favourable for La Nina," the administration said.

Elwynn Taylor, a climatologist at Iowa State University, said that a La Nina had a 25% of developing before the end of next month.

"The sea temperature is cooling from Tahiti east, a La Nina indicator, and the atmospheric pressure is highest in a month at Tahiti, another indicator," Professor Taylor said.

"The drought risk is real… for the Corn Belt. Some [crop] market scares are likely."