Hurricane Gaston reforms in Atlantic Ocean

A storm churning in the Atlantic Ocean strengthened into a hurricane on Saturday as a separate system threatened to dump rain on Florida, sparking fears about standing water amid a battle against Zika virus.

Hurricane Gaston was around 655 miles east-southeast of Bermuda and was moving northwest at 8 mph as of 11 p.m., the National Hurricane Center said. It had maximum sustained winds of 85 mph. The hurricane had previously weakened to a tropical storm before regaining strength Saturday.

Forecasters expect the hurricane to slow down and swing north by Monday, and there are no warnings issued for land. The storm could strengthen Sunday or Monday, the hurricane center said.

Meanwhile, a storm system in the Caribbean was producing showers and storms in Cuba but could bring rain to Florida — something that could cause standing water to collect and add a challenge to the state's efforts to combat the mosquito-borne Zika virus, officials said.

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The low pressure system could bring rain to southern Florida and the Florida Keys by Sunday, forecasters said.

The system was large but disorganized Saturday night, but it has a 40 percent chance of turning into a tropical cyclone over the next 48 hours, the hurricane center said. A tropical cyclone doesn't necessarily mean a destructive storm like a hurricane, but just a rotating organized system.

"As this system moves into the Gulf of Mexico it will have a greater potential to organize, so it still poses a significant risk, and we are urging everyone to remain vigilant and to prepare for this possible scenario," Florida Department of Emergency Management Director Bryan Koon said in a statement.

Florida officials urged residents to dump any water that collects. Florida has confirmed nearly 600 infections of Zika, a virus that can cause severe birth defects when pregnant women are infected — including microcephaly, a condition where the head is unusually small.

SEE MORE: New images show devastating impact of Zika on babies' brains

The vast majority of those cases are related to travel to countries experiencing Zika transmission, areas that include much of Latin America and the Caribbean.

But more than 40 cases of locally transmitted Zika have been confirmed in Florida, and there have been outbreaks in an area of Miami and Miami Beach. On Tuesday, a case was reported on Florida's Gulf coast.

Scroll through to see how Zika is spreading in Miami:

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