A Heat Advisory has been issued for south central and southeast Texas, including the Houston area until Sunday evening. The National Weather Service issued the alert as heat index values are expected to soar up to 112 degrees. DOWNLOAD THE FOX 26 HOUSTON APP BY CLICKING HEREAccording to officials, the heat advisory will be in effect until 7 p.m. Saturday evening and then be back in effect from noon to 7 p.m. on Sunday. The combination of high temperatures and elevated humidity levels increases the risk of heat-related illnesses. Residents are advised to drink plenty of fluids and avoid staying in the sun for prolonged periods of time.