I am worried about my local cool weather, too. However, I just check the Sept forecast. This streak of cool weather (70 high, 50 low) will last until Sept 12. Then, it will be back to warmer weather ( high 80-90) for the rest of the month.
All I can say is that the second half of Aug felt like the fall while the second half of Sept will feel ilke Aug. at least, it will give me some hope that my wm will ripen later this month.