MIAMI - Tropical Storm Dora is gaining some muscle as it swirls in the Pacific Ocean off Mexico.

The U.S. National Hurricane Center in Miami said the storm was centred early Tuesday about 485 kilometres south of Puerto Angel, Mexico, and moving west at 26 kph with top sustained winds of 100 kph.

It is expected to become a hurricane by Tuesday. No watches or warnings are in effect yet.

In the Atlantic, Tropical Storm Bret was moving slowly north-northeast from the Bahamas and forecast to stay away from the U.S. East Coast.

Bret's maximum sustained winds were 85 kph. Its centre was about 330 kilometres north-northeast of Great Abaco Island.