The temperature in Washington has topped 90 degrees for 12 straight days. While I was sitting inside during one of those days trying to avoid the heat, I spent some time making a chart. You can see it above.
It shows the average number of days per year when the temperature cracked 90 degrees in various cities, during the first eight decades of the 20th century (before global warming became more severe), and then in the past 10 years.
I chose 15 major cities from the National Weather Service’s database, without knowing exactly what I’d find. In four of the cities, mostly in the Midwest, the numbers are virtually unchanged. But in the other 11, there has been a substantial increase. Houston, for example, used to have 89 days above 90 degrees in a typical year; it now has 115. Atlanta has gone from 36 to 56, and Denver from 27 to 48.
By this measure, the Boston of today feels like the New York of the 20th century. Washington is on its way to resembling the Memphis of old. And Miami is more like Dallas used to be.