Bertha is now a Category Three hurricane but is expected to weaken before it reaches Bermuda on Saturday.

The first hurricane of the season, the tropical storm was upgraded yesterday afternoon as Bertha gained sustained winds of 100 knots with gusts of 120.

At present, the system is about 1,000 miles south south-east of the Island.

Forecasters predict Bertha will curve north west and pass to the east of Bermuda on Saturday.

By then however, the hurricane is expected to lose strength, reverting back to Category One status.

The wind speeds of a Category Three hurricane are 111-130 mph, while a Category One reaches 74-95 mph, according to the Saffir-Simpson scale.

Meteorologists cannot predict whether Bertha will make landfall in Bermuda, but are advising residents to take necessary precautions.

Nick Camizzi, a forecaster at Bermuda Weather Service, said last night: "As of the 6 p.m. advisory, Bertha is now a major storm.

"It is a potential threat to Bermuda because its closest point of approach in the next 72 hours is 372 nautical miles to the south south-east, and it is expected to get closer to us beyond the 72 hours projection.

"Bertha will still be approaching us at day five (Saturday). The centre of the forecast now is just a bit to our east."

Mr. Camizzi said the US National Hurricane Center in Miami predicts Bertha may fall back to a Category One storm "in the next few days".

"It looks like it will begin to weaken on Wednesday but it is still expected to be a hurricane as it moves north to Bermuda," he said. "We will continue to monitor it and ask everyone to prepare for the worst and to take precautions."

Mr. Camizzi said it was "unusual" for a storm to develop off Africa so early in the season.

Bertha formed on Thursday near the Cape Verde Islands.

It is the second storm of what is predicted to be an above-average hurricane season.

The first named storm of 2008 — Arthur, formed in the day before the season officially began on June 1, and passed over southern Mexico and Central America.