Joaquin has been downgraded to a Category Three hurricane as it heads towards Bermuda where it is expected to dump rain and generate damaging winds, forecasters say.
The hurricane's centre is expected to pass near Bermuda on Sunday afternoon, the US National Hurricane Center said in its latest statement.
Joaquin's outer rainbands were already thrashing the island early on Sunday, with dangerous winds forecast to follow, the NHC said.
However, additional weakening is expected over the next 48 hours, as the Category Three storm on the five-point Saffir-Simpson scale continues to decrease, it added.
Joaquin was swirling 340 kilometres southwest of Bermuda as it travelled northeast at 33km per hour.
Three to five inches of rain "are expected across Bermuda through tonight," the NHC said, and significant coastal flooding is forecast.
The NHC said that swells generated by Joaquin were still affecting the Bahamas, where homes were destroyed and residents left without power or phone services after the hurricane tore past.
The southeast United States has already been battered by a separate weather system that has caused significant flooding.
That region is also seeing Joaquin-related swells that "are likely to cause life-threatening surf and rip current conditions," the NHC said.
"Even though Joaquin is expected to pass well east of the coast of the United States, a prolonged period of elevated water levels and large waves will affect the mid-Atlantic region," it added.