Severe Expected Likely Extreme Heat Warning Extreme Heat Warning issued August 17 at 11:29AM CDT until August 19 at 9:00PM CDT by NWS Tulsa OK Aug 18, 1:00 PM → Aug 19, 9:00 PM WHAT: Dangerously hot conditions with heat index values up to 111expected. WHERE: Portions of east central and northeast Oklahoma. WHEN: From 1 PM Tuesday to 9 PM CDT Wednesday. IMPACTS: Heat related illnesses increase significantly duringextreme heat and high humidity events. + Read More Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Updated: Aug 17, 6:23 PM Source: NWS Alert