This phenomenon only happens in Hawaii . . . and Cuba & Nigeria & Indonesia & Peru & Sudan & Laos &…

I remember being a little confused by your aside question when I first came across it in 1989:  
"Why doesn't the hottest day of the year match the longest day of the year?"    The answer is pretty complex.  It took a few years to fully understand the concept.
I seem to recall that it has something to do with the difference between net incoming solar radiation and net outgoing infrared radiation.  For the atmosphere to cool down, the amount of outgoing IR radiation needs to surpass the amount of incoming solar radiation.  During the spring and summer months, from late March until late  September the sun is in the sky longer.  So there is more daylight.  However, just because there is more daylight does not mean that the incoming solar radiation will surpass the outgoing IR radiation.  It is only during that period of time, between mid May and mid August, when the angle of the sun increases to a point where incoming solar radiation will outpace outgoing IR radiation, that the atmosphere will start to heat up more than it cools down. As long as the net amount of incoming radiation surpasses the net amount of outgoing radiation, the atmosphere will continue to heat up...even beyond the summer solstice, which is the longest day of the year.