Hurricane Erin regained Category 4 strength Sunday night as its outer bands pounded the Virgin Islands and Puerto Rico with gusty winds and heavy rains.

Hurricane Erin restrengthened into a Category 4 storm late Sunday, with forecasters warning it is expected to intensify and grow in size in the coming days as it lashes Caribbean islands with heavy rains that could cause flash floods and landslides.

Over the weekend, northern portions of the Leeward Islands, the Virgin Islands, and Puerto Rico are expected to receive tropical rain ranging from 2 to 4 inches, with isolated totals up to 6 inches. Flash flooding, landslides and mudslides will be the main concerns over the next several days.

U.S. shores are unlikely to see a direct hit, but a strong offshore hurricane can produce massive and dangerous waves well away from its center.

Powerful Hurricane Erin has undergone a period of astonishingly rapid intensification — a phenomenon that has become far more common in recent years as the planet warms. It was a rare Category 5 for a time Saturday before becoming a Category 4,

Spaghetti models predict Erin will skirt the U.S. East Coast by hundreds of miles as it moves north through next week.

The NHC said it currently expected Erin to become a Category 4 storm later Saturday but to eventually swerve away from the continental United States.

Hurricane Erin is forecast to remain well offshore but still bring hazardous currents and possible erosion like previous offshore hurricanes before it.