High humidity on Wednesday combined with summertime heat created feels-like temperatures near 110 degrees.
The National Weather Service issued a heat advisory until 7 p.m. for Brazoria, Chambers, Fort Bend, Galveston, Harris, Jackson, Liberty, Matagorda and Wharton counties.
Forecasters said heat index values of 106 to 110 degrees will be seen across the advised area.
Officials reminded people to take frequent breaks in air-conditioned places, wear lightweight, light-colored clothing and drink plenty of non-alcoholic, caffeine-free beverages.
It is never safe to leave children or pets unattended in a vehicle, officials said.