Hurricane Ophelia became a "rare" Category 3 about 220 miles south of the Azores islands as it heads towards Ireland and the United Kingdom, the National Hurricane Center announced Saturday morning.

The storm, which has 115 mph sustained winds, became the sixth major hurricane of the season, which ends on Nov. 30. According to the Saffir-Simpson Hurricane Wind Scale, this makes Ophelia a "major" hurricane capable of "devastating damage."

Ophelia is expected to gradually weaken tonight into Sunday before it reaches Ireland by Monday, the NHC said.

It is rare for an Atlantic hurricane to move northwest towards Europe; usually, such tropical storms pose more of a threat to the Caribbean and the Americas. Four separate hurricanes have made landfall over the U.S. so far in 2017, the first time this has happened since 2005.

The storm is also significant in terms of history, as it tied a record not seen in more than a century.

Dr. Phil Klotzbach, a Colorado State University tropical meteorologist, noted upon Ophelia's upgrade to a hurricane this week, that the last time 10 straight tropical storms became hurricanes was in 1893, and once in each of the two preceding decades.

Damage associated with Ophelia, which threatens to bring heavy rain to Ireland and the U.K., could result in several million dollars worth of damage in both countries, according to one estimate from Chuck Watson, a disaster modeler at Enki Research in Savannah, Ga., Bloomberg reported.