Tropical Storm Seymour is strengthening not far from Mexico's coast and forecast to become a hurricane on Monday.

The National Hurricane Center said Sunday night that the storm is centered about 370 miles (595 km) south-southwest of Manzanillo, Mexico, and has maximum sustained winds of 50 mph (80 kph).

Seymour is moving west-northwest near 15 mph (24 kph), and this general motion is expected continue over the next couple of days.

Additional strengthening is forecast during the next 48 hours, though it is not currently a threat to land.