The storm is moving toward the west near 13 miles per hour (20 km/h).
Oscar is the 15th named storm this season, the 7th storm to be subtropical.
The Bermuda Weather Service said the storm was moving west at about 19.5 mph with winds of more than 64 mph and gusts of 79 mph.
At 1100 a.m. AST (1500 UTC), the center of Subtropical Storm Oscar was located near latitude 27.3 north, longitude 48.4 west. Tropical Storm Nadine was no threat to land earlier this month. Regardless of strength, Hurricane Oscar is not expected to be a threat to land.More news: OnePlus 6T will reportedly include bigger battery, in-display fingerprint sensor
There were no coastal watches or warnings in effect.
A front is still on track to push Oscar early this week and turn it quickly northeast before even reaching Bermuda. Then, Oscar is forecast to begin moving toward the north Monday night or Tuesday, and then head northwest away from the United States by Wednesday.
The 2018 Atlantic hurricane season officially started June 1, and it will end on November 30, the NHC said. The tropical depression that would eventually become Hurricane Kate formed southeast of the Bahamas on November 8th.