Since the new normal in this world we live in is that 90 degree days have never ever happened before (see mid May), looking at the long range I really don't see anything that suggests prolonged hot weather anytime soon. Either they will be cut off after a couple of days by some sort of back door cold front, or the overall pattern will favor weather systems moving along from west to east so cold fronts will cut the heat off just as it gets going.
The stretch of 90 plus temperatures about to arrive will last from Sunday through Tuesday of next week. This will be 3 days of 90 plus which meets the dumb down rule for a heatwave (old definition was 5 days). All weather models show a back door front pushing through the area from north to south late Tuesday or Tuesday evening. This means that Wednesday and Thursday will be cooler especially near coastal areas as winds will be from the east. ALL WEATHER MODELS show this backdoor and latest runs show the push of cool air to be a bit stronger than previously modeled.
READ MORE ON THE LONG RANGE INCLUDING THE CHANCES FOR TROPICAL DEVELOPMENT AT http://www.meteorologistjoecioffi.com/index.php/2017/06/09/long-range-looks-cooler-average-overall/