New York City has not had a daily high temperature above 100 degrees since 2012, and it has had only five such days since 2002. However, in a previous 18-year span from 1984 through 2001, New York City had nine days at 100 degrees or higher. When the power went out in New York City earlier this month, the temperature didn’t even get to 100 degrees – it was 95, which is not extreme. For comparison, there were 12 days at 95 degrees or higher in 1999 alone.
Kansas City, Missouri, for example, experienced an average of 18.7 days a year at 100 degrees or higher during the 1930s, compared to just 5.5 a year over the last 10 years. And over the last 30 years, Kansas City has averaged only 4.8 days a year at 100 degrees or higher, which is only one-quarter of the frequency of days at 100 degrees or higher in the 1930s.
Here is a fact rarely, if ever, mentioned: 26 of the 50 states set their all-time high temperature records during the 1930s that still stand (some have since been tied). And an additional 11 state all-time high temperature records were set before 1930 and only two states have all-time record high temperatures that were set in the 21st century (South Dakota and South Carolina).
So 37 of the 50 states have an all-time high temperature record not exceeded for more than 75 years. Given these numbers and the decreased frequency of days of 100 degrees or higher, it cannot be said that either the frequency or magnitude of heat waves is more common today.