Experts at Colorado State University have adjusted this year’s Atlantic hurricane forecast, increasing the number of storms expected.

Nine named storms were forecast in April, but this has been changed to 10 – with the number of hurricanes lifted from three to four.

The season should still be below average because the tropical Atlantic is cooler than usual and an El Nino system – which tends to reduce hurricane activity – is developing.

“However, the transition to El Nino has slowed some in recent weeks and the tropical Atlantic has anomalously warmed, causing us to increase our forecast,” the university says.