1953 and 1966 have a record that NYC may never match ever again, 4 days of 100+
I used to think 1966 was more impressive, but 1953 has so many records, two straight days of 100+ in two separate heatwaves, NYC's longest heatwave on record (late August into September to boot) and a second very long heatwave to boot back in July when they had their first 2 day stretch of 100+.
What 1966 did that only happened two other times (in 1948 and more recently in 1993) was have three straight days of 100+. And those three straight days of 100+ happened at all of our major reporting sites-- including JFK!