ATLANTA (REUTERS) - Hurricane Humberto is expected to become a major hurricane with 178kmh winds by Tuesday night (Sept 17) or early Wednesday, forecasters said, as the storm tracked towards Bermuda after strengthening early on Tuesday.

The Miami-based National Hurricane Centre (NHC) warned that Bermuda could be hit with tropical storm force winds and up to 8cm of rain by Wednesday, and was at risk of life-threatening waves and tides.

The centre of the hurricane is expected to approach the archipelago on Wednesday night, the NHC said, and current tracks show it side-swiping Bermuda's west coast on Thursday .

Packing 150kmh winds early on Tuesday morning, Humberto was 920km west of Bermuda, picking up speed and moving at 13kmh, the forecasters said.

After gaining hurricane strength late on Sunday, Humberto dropped another 5cm of rain on the storm-ravaged north-western Bahamas as it churned away from the US coast, the NHC said.

It is bringing life-threatening waves and tides to parts of the US east coast from Central Florida to North Carolina and dangerous conditions will remain for the next few days, forecasters said.