MIAMI — Tropical Storm Nicholas was expected to strengthen as it headed for the Gulf Coast on Sunday, threatening heavy rain and floods in coastal areas of Texas, Mexico and Louisiana.

Forecasters at the National Hurricane Center in Miami said a hurricane watch and storm surge warning were issued for a portion of Texas, while tropical storm warnings were issued for coastal areas of Texas. Nicholas is expected to produce total rainfall of 5 to 10 inches (13 to 25 centimeters), with isolated maximum amounts of 15 inches, across portions of coastal Texas into southwest Louisiana on Sunday through midweek. The hurricane watch was issued for the coast of Texas from Port Aransas to Sargent.

The storm was expected to bring the heaviest rainfall west of where Hurricane Ida slammed into Louisiana two weeks ago. Meteorologist Bob Henson at Yale Climate Connections predicted rainfall could still plague places where the hurricane toppled homes, paralyzed electrical and water infrastructure and left at least 26 people dead.