Tropical Storm Oscar was heading toward the Bahamas late on Monday after dumping heavy rain across eastern Cuba.

Its maximum sustained winds were blowing at 40 miles per hour late as Oscar moved north-north east at eight mph, about 105 miles south of Long Island, Bahamas, the US National Hurricane Centre in Miami said.

A tropical storm warning was in effect for the central and south eastern Bahamas.

Tropical Weather
This satellite image provided by NOAA on Saturday shows Hurricane Oscar. (NOAA via AP)

Oscar is the smallest hurricane on record, with a wind field of only about six miles across, according to hurricane specialist and storm surge expert Michael Lowry.

He noted that not a single forecast model indicated that Oscar might strengthen into a hurricane on Saturday before making landfall in the Bahamas.

“It’s not often we see a colossal failure in hurricane forecasting,” he wrote in an analysis published Monday.

Oscar was a Category 1 hurricane with winds of 75 mph when it made landfall in the eastern Cuban province of Guantanamo, near the city of Baracoa, on Sunday evening.

Flooding in low-lying areas was reported and at least six deaths.

Cubans were already suffering from a major power outage that has knocked out power and water across the island since last week.

Oscar earlier made landfall on Saturday on Great Inagua in the Bahamas, where residents were evacuated after their homes were damaged.

Meanwhile, Tropical Storm Kristy formed off Mexico’s southern Pacific coast on Monday.

The storm was 315 miles south west of Acapulco and was moving west at 16 mph. It had sustained winds of 45 mph, according to the National Hurricane Centre.

Kristy was forecast to strengthen into a hurricane on Wednesday but continue moving over open waters without threatening land.