The U.S. National Hurricane Center says Tropical Storm Calvin has formed in the Pacific Ocean off southern Mexico.
A bulletin from the center says Calvin is centered about 70 miles (110 kilometers) east-southeast of Puerto Angel and moving to the west-northwest at 2 mph (4kph).
It has maximum sustained winds of 40 mph (65 kph).
A tropical storm warning is in effect for the Mexican coast between Punta Maldonado to Boca de Pijijiapan.
The center said Monday that Calvin is the third tropical storm of the season in the eastern Pacific.