One factor: 38% of population in NYC had air conditioning in 1970, 90% do now.
The OP mentioned this as a symptom - "20 years ago I rarely used AC in the summer, now its on nearly every day from May to September." Increased AC use and the associated waste heat is a significant contributor to the urban heat island effect. https://news.asu.edu/content/excess-heat-air-conditioners-ca....
How does that explain the change in long term weather when the city is already heavily developed.
One factor: 38% of population in NYC had air conditioning in 1970, 90% do now.
The OP mentioned this as a symptom - "20 years ago I rarely used AC in the summer, now its on nearly every day from May to September." Increased AC use and the associated waste heat is a significant contributor to the urban heat island effect. https://news.asu.edu/content/excess-heat-air-conditioners-ca....