South Texas will be on the edge of upper-level high pressure through Friday, then build back over the area resulting in a continuation of the serious heat and Saharan dust.
Tonight, we will have fair but hazy skies, warm and sticky, with a low of 78.
Thursday, expect hazy sunshine and high heat in and around isolated showers and a high of 97. Heat index to 115.
Thursday night will be warm and stuffy, with a low of 79.
Friday, expect scattered showers, so, not quite as hot, with more clouds and less wind and a high of 94. Heat index to 108.
The tropics are active, but nothing as of now poses a threat here.