MIAMI (AFP) - Tropical Storm Danny was upgraded to a hurricane on Thursday, the first of the Atlantic season, as it barrelled through the Caribbean, forecasters said.

"Danny strengthens into the first hurricane of the 2015 Atlantic hurricane season," the Miami-based National Hurricane Centre said.

The hurricane was located 1,755km east of the Windward Islands in the Caribbean, with maximum sustained winds of 120kmh, the forecasters said.

The hurricane remained far from land, and the NHC said there were no coastal watches or warnings in effect.

But the centre said Danny could become more powerful in the coming days.

"Some additional strengthening is forecast during the next 48 hours," it said.

Danny was travelling west-northwest at a speed of 19kmh, and was expected to continue along the same path.

Experts said earlier this month that there was a 90 per cent chance the 2015 hurricane season in the Atlantic would be less active than usual.

They said this may be due to the strong El Nino weather pattern that is unfolding this year.