Dolly made landfall near South Padre Island, Texas, Wednesday afternoon as a Category 1 hurricane, packing winds of 95 mph.
The storm briefly intensified to a Category 2 hurricane with winds of 100 mph prior to making landfall.
Dolly is expected to produce heavy rains, flooding and coastal storm surges, according to the National Hurricane Center.
The threat of levees breaking in the Rio Grande Valley, an agricultural and farming region near Brownsville, is a real concern. Emergency management officials urged residents to evacuate low-lying areas along the Texas-Mexico border.
Dolly's strong winds forced the closure on Tuesday of the causeway to Padre Island, a barrier island near Corpus Christi and a popular vacation spot. Most tourists and residents evacuated before the causeway closed.
More than 1,200 National Guardsmen were activated Tuesday by Texas Governor Rick Perry.