If a storm is a Category 3, 4 or 5, it is deemed a "major" hurricane due to the potential for "significant loss of life and damage," the National Hurricane Center says. Hurricanes that fall into categories 1 or 2 are still considered dangerous, the center says.

Hurricane Erin has been downgraded to a Category 3 hurricane. A tropical storm warning is in effect for the Turks and Caicos Islands as winds and heavy rains hit the Virgin Islands and Puerto

Hurricane Erin was downgraded to Category 3 early morning on Sunday, Aug. 17, per the National Hurricane Center. However, the tropical storm is still expected to bring 'life-threatening' conditions to the beaches along much of the east coast of the U.

Hurricane Iona has strengthened into a Category 3 storm far southeast of the Hawaiian Islands. The NHC is also tracking more in the Pacific.