Cameron, Hidalgo and Willacy counties will be under a heat advisory from 1 to 7 p.m. Thursday. Near record temperatures combined with elevated daytime humidity will produce dangerously high heat indices, according to the National Weather Service in Brownsville.
Temperatures will feel like they are between 111 and 115 degrees.
Rio Grande City (102 degrees) and McAllen (101) are expected to reach triple-digit high temperatures. Brownsville will be 97 and South Padre Island 86.