Danny is the official first hurricane of the 2015 Atlantic season, according to the US National Hurricane Center, which upgraded the tropical storm when winds from Danny gusted up to 75 miles per hour, eking into hurricane status by exceeding 74 mph.
Danny, a Category 1 storm, could weaken back into a tropical storm before reaching Puerto Rico on Tuesday, according to the Miami-based hurricane center's five-day outlook.
"Danny is a small tropical cyclone," the center said, adding that hurricane-force winds extended only 10 miles from the eye of the storm.
Danny is at the low end of the five-step Saffir-Simpson scale of intensity, and is the fourth named storm of the 2015 hurricane season, which forecasters have predicted would be quieter than normal, partly due to the El Niño weather pattern.
Forecasters said they expect Danny to remain a low-strength Category 1 hurricane as it heads west, according to NBC News.
Hurricane Danny is projected to make landfall in the Lesser Antilles by Monday morning and Puerto Rico could see downpours and sharp winds by Tuesday. By then reports say it could be downgraded, either to a tropical storm or tropical wave. National Oceanic and Atmospheric Administration cautioned that the compact size of the hurricane makes it difficult to predict, and that Danny is subject to fluctuations in strength, both up and down.
Forecasters have yet to say if it could reach South Florida before dissipating.
The latest US government projections are for six to 10 named storms this season, with as many as four reaching hurricane status.
This storm season, which runs from June 1 through Nov. 30, only one of the expected storms is anticipated to develop into a major hurricane, according to the NOAA.
This report contains material from Reuters.