Tropical Storm Barry formed off Mexico's Gulf Coast on Wednesday, prompting Mexican authorities to ready hundreds of shelters.
The U.S. National Hurricane Center in Miami said the Atlantic hurricane season's second tropical storm was drenching areas in its path with up to 10 inches of rain in some places, raising the threat of flash floods.
In the late evening, Barry was about 40 miles (60 kilometers) northeast of Veracruz, Mexico, and was expected to make landfall near that port city Thursday morning.
The center predicted Barry would strengthen slightly before making landfall but said it would weaken soon after.
Veracruz state Civil Protection Secretary Noemi Guzman said 2,000 shelters had been readied in the state with mattresses, blankets, water and canned food. She said the shelters at schools and recreation centers could house up to 306,000 people.
The port of Veracruz was closed to small vessels because of the strong winds, Guzman said.
The storm had maximum sustained winds of 45 mph (75 kph). It formed as a depression off the coast of Belize on Monday and began moving north.
A tropical storm warning was in effect on the Mexican coast from Punta El Lagarto to Tuxpan, in Veracruz state.
Meanwhile, late-night storms rumbled across Central Florida for the third straight day, dropping heavy rain on parts of the region.
There's a 40 percent chance of rain in the Orlando area on Wednesday, with high temperatures reaching the mid-90s. The "feels like" temperature, however, will be 100 degrees.
Rain chances drop to 20 percent on Thursday in Central Florida before jumping to 40 percent from Friday through Sunday.