Only one Category 5 hurricane has ever made landfall on the island of Puerto Rico, an unincorporated territory of the United States.
That was the 1928 Okeechobee hurricane that crossed the island with sustained winds of 160mph and caused more than 300 deaths on the island.
Now, Hurricane Maria seems likely to become the second Category 5 to hit Puerto Rico.
As of 5pm ET, the storm is intensifying, with 165mph sustained winds.
Critically, the storm's central pressure is also falling, and it is down to 916 millibars as of Tuesday evening.
At that central pressure, Maria would rank among the 10 most-intense landfalling hurricanes in the Atlantic basin in the last 150 years.