Heavy rains and high winds are battering Guam and the Northern Marianas ahead of the arrival of a "very dangerous" storm that could cut power supplies for weeks or months.

Super Typhoon Bavi arrived in the US Pacific Island territories of Guam and the Northern Marianas, bringing torrential rains and hurricane-force winds.

According to the National Weather Service, Bavi made landfall on Monday on Rota, the southernmost island of the Marianas.

"The western eyewall of Super Typhoon Bavi is currently moving over the island of Rota. The latest forecast intensity is at 180 mph (290 kph) as it passes over Rota," the NWS said. "Catastrophic winds exceeding 150 mph will continue across Rota during eyewall passage."

Bavi was forecast to move westwards over the archipelago in the western Pacific Ocean on Monday morning, packing maximum sustained winds of 280 kilometers (173 miles) per hour and gusts of 333 km/h, the Joint Typhoon Warning Center said.