MIAMI: Hurricane Irma, which has toppled cranes, swallowed streets and left millions without power, was starting to weaken on Monday while still pummeling parts of Florida on its destructive march north., reports AFP.

Irma was downgraded to a Category 1 hurricane early Monday and forecasters expect it would become a tropical storm later in the morning, but warnings of hazardous storm surges persisted in several areas even after the worst of Irma's ferocity had passed.

Maximum sustained winds had decreased to 75 miles per hour as of 5:00 am local time (0900 GMT) as Irma blazed its disastrous path through Florida, where more than six million people had been ordered to flee in one of the biggest evacuations in US history.

The massive storm's center was forecast to move near the northwestern coast of Florida before crossing into the state of Georgia later into Monday. The National Hurricane Center cautioned that tornadoes remained possible in northeast Florida as well as southeast parts of Georgia and South Carolina into the evening.