With temperatures soaring and the heat index reaching critical levels, Houstonians grappled with the sweltering heat today. Local authorities have responded by activating cooling centers across the city to help residents cope with the dangerously high temperatures. The National Weather Service has issued a heat advisory for the area, signaling conditions that pose a heightened risk of heat-related illnesses. RELATED: Heat Advisory issued for Houston area until June 30Swimmers were cautious. The City of Houston's initiative to open cooling centers is a proactive measure to protect its citizens.