Tropical Storm Dora grew to near-hurricane force in the Pacific Ocean Tuesday on a track that would keep it offshore from Mexico.
The U.S. National Hurricane Center in Miami said the storm was centered about 265 miles (425 kilometers) south of Puerto Angel and it was moving west-northwest at 15 mph (24 kph) with top sustained winds near 70 mph (110 kph).
Its proximity to the coast prompted Mexican authorities to issue heavy-rain warnings in the Pacific coast states of Guerrero and Oaxaca.
In Guerrero, the government was preparing nearly 900 shelters in flood-prone areas along the coast, which includes the resort city of Acapulco.
In Oaxaca, authorities closed at least two beaches where the storm is expected to hit the hardest.
Forecasters said it could become a major hurricane Wednesday, with winds of more than 110 mph (177 kph).
In the Atlantic, Tropical Storm Bret was forecast to weaken as it moves northeast away from the Bahamas and well off the U.S. Atlantic coast.
Bret's maximum sustained winds were 50 mph (85 kph). Its center was about 365 miles (590 kilometers) south of Cape Hatteras, North Carolina.