Officials in Puerto Rico, already soaked from days of rain, are warning residents to prepare for more.
Omar's maximum sustained winds are near 75 mph (120 kph) early Wednesday. But the National Hurricane Center in Miami says it's expected to strengthen.
Omar is centered about 285 miles (455 kilometers) south-southwest of San Juan, Puerto Rico, and moving near 7 mph (11 kph).
Meanwhile, a tropical depression is hugging the coast of Honduras. A tropical storm warning is in effect for the entire coast of Honduras.