Weather patterns are variable and sometimes what is important isn't necessarily just the peaks and troughs but the averages. For example, we were hitting or surpassing record highs in the Southeast June through August but the rest of the year had significantly higher rainfall and importantly, average temperatures were also above normal.

Most of it is probably just normal statistical variation, but a low/moderate ENSO index (which we had over this summer) is actually associated with somewhat lower average summer temperatures in most of the United States. The North Atlantic Oscillation, which is a similar quasi-periodic cycle in (shockingly) the North Atlantic, also tends to cause somewhat lower temperatures on the East Coast when it is in its negative index phase, which (again) it was over this summer. Both these influences are dominated by inter-annual variability on smaller scales, though.