With maximum sustained winds of 130 kilometers per hour (80 miles), the tropical storm has gained strength and has already become a hurricane as it approaches the island, where it threatens heavy rains, flooding and mudslides.
With this decision, the President has ordered the Department of Homeland Security and the Federal Emergency Management Agency (FEMA) to carry out the necessary efforts to "save lives; protect property, health and public safety; and prevent a catastrophe in the 78 municipalities" of Puerto Rico.
The U.S. federal government will finance 75% of the emergency measures, according to a White House press release.
The U.S. National Hurricane Center (NHC) has reported that it is a category 1 hurricane, out of a total of 5 on the Saffir-Simpson scale.
Fiona is located 80 kilometers south of Ponce (Puerto Rico) and is moving northwest at 13 kilometers per hour.
The hurricane has "very dangerous winds" that are expected to affect first Puerto Rico and then the Dominican Republic.
These winds, it notes, are a risk for falling trees and branches that can also cause extensive damage to power lines and poles causing outages that could last from "a few to several days".
The NHC has lifted the hurricane warning for the U.S. Virgin Islands. After its passage over Puerto Rico, Fiona is forecast to move near the north coast of the Dominican Republic on Sunday night and Monday, and near or east of the Turks and Caicos Islands on Tuesday.