Hurricane Leslie was downgraded to a tropical storm as it swirled over the Atlantic on a track toward Bermuda but is expected to regain hurricane strength before passing by the island on Monday (NZ time), the US National Hurricane Center reported.

A wealthy British overseas territory and global reinsurance center, Bermuda is not expected to take a direct hit from Leslie, which could re-strengthen to a Category 1 hurricane, the lowest on the Saffir-Simpson scale of intensity.

Leslie then is expected to intensify into a Category 2 hurricane with wind speeds of 100 mph (160 kph) on Tuesday (NZ time).

Forecasts show the storm will veer slightly east of the tiny island of 20 square miles (52 square km) with 65,000 residents.

Residents in the rocky archipelago stocked up on food and water - as well as alcohol, for traditional hurricane parties. Most government offices and all of the island's schools and beaches were closed on Friday.

Some of the island's hotels have advised guests to consider leaving early before the worst of the storm is felt.

Tropical storm-force winds are expected to batter the island located 640 miles (1,030 km) off the east coast of the United States, as the season's sixth Atlantic hurricane follows its slow trajectory northward.

The Miami-based National Hurricane Center said Leslie was about 390 miles (630 km) south-southeast of Bermuda moving in a northerly direction at 5 miles per hour (7 kph), with maximum sustained winds of 65 miles per hour (100 kph). Before being downgraded to tropical storm status, Leslie had spent two days as a Category 1 hurricane over the Atlantic.

The large span of storm winds combined with its slow movement "will produce large waves and life-threatening rip currents on Bermuda and along much of the US East Coast through the weekend," the hurricane center said.

Southeasterly swells have been generating hazardous surf and rip currents in Bermuda's waters since Wednesday.

Farther out in the ocean, Hurricane Michael, the first Category 3 storm of the Atlantic hurricane season, was downgraded to Category 2 yesterday.

Michael was moving north today, about 930 miles (1,495 km) west-southwest of the Azores, and was not a threat to land.

It had maximum sustained winds of 105 mph (165 kph). A gradual weakening is expected during the next 48 hours, the hurricane center said.

- Reuters