2010 agrees well with my own observations that it was our hottest summer EVER :-)
However I found both 2016 and 2005 to be lackluster because of lack of 100 degree temps on the coast.
I have my own list for the hottest summers and these are them in chronological order:
1991
1993
1999
2010
2011
honorable mention goes to 1983 and 1995 and 2002.
I find the number of 90 degree days and number of 100 degree days to be more important than avg temps when I gauge which summers are the "hottest."
That 10 day streak of 90+ and 3 straight 100+ in July 1993 really stand out to me as the hottest weather I've ever experienced here.
The streak of 3 days out of 4 at 100+ at JFK in 2010 comes close, but that was a drier (nicer) heat.
Overall though 2010 > 1993 and they are both in my short list for hottest summers.
If I had to go back in time I'd say 1966 belongs on this list too, possibly second only to 2010 for its streak of 100+
And 1953 because of that record streak of 90+ and 100+ in late August and September!