The National Weather Service in Flagstaff says the Excessive Heat Warning issued for Grand Canyon elevations below 4,000-feet has been extended and is in effect through 7-pm Thursday. Upper-level high pressure lingers over the Southwest U.S. causing very hot temperatures to continue Thursday and into the weekend. Afternoon highs will be roughly 10 degrees above seasonal averages. A few isolated thunderstorms with localized strong gusts are in the forecast with the best chance for rain on Thursday. However, most areas will remain hot and dry.
