US hurricane researchers have slightly increased their storm activity forecast after previously warning of an above-average Atlantic season. 

Colorado State University experts expect 25 named storms, up from 23 previously, and say 12 hurricanes are likely to form, up from 11 in the earlier outlook. Six storms are anticipated to reach “major” strength. 

Hurricane Beryl has already become the earliest Atlantic-season hurricane to reach category 5 strength. The system crossed the Texas coastline early on July 8 at category 1 intensity. 

The forecasters expect La Nina conditions will develop by the peak of the season, reducing wind shear, while extremely warm sea surface temperatures are conducive to hurricanes. 

“Hurricane Beryl, a deep tropical category 5 hurricane, is also a likely harbinger of a hyperactive season,” they say. “This forecast is of above-normal confidence.” 

The forecast includes a well above average probability of major hurricanes making landfall along the continental US coastline and in the Caribbean. 

Risk modelling firm KCC estimates privately insured losses from Beryl will be close to $US510 million ($752 million) in the Caribbean, $US90 million ($133 million) in Mexico and $US2.7 billion ($4 billion) in the US. 

More than 2.5 million homes lost power in Texas after Beryl hit and a storm surge reached 1.8 metres in some areas. The centre of the storm passed through Harris County, bringing tropical storm-strength winds to Houston. 

Beryl began as a tropical depression over the central tropical Atlantic on June 28, rapidly intensified to a category 3 hurricane in just 42 hours and strengthened as it moved across the Caribbean.