Central regions of the United States are expected to have above average highs for the next three days. Dallas, Texas and Denver, Colorado may see temperatures 8 degrees higher than average. The National Weather Service has issued a heat advisory for many counties in the eastern half of Oklahoma. This advisory is in effect until later this evening (Thursday, July 11, 2013).
Intense heat combined with humidity will cause dangerous conditions, thus limited outdoor activity with frequent breaks is recommended. Stay aware of signs of heat exhaustion and stroke in case of emergency.
Signs of heat-related illness: http://firstaid.webmd.com/understanding-heat-related-illness-symptoms