I still remember how hot the summer of 1993 felt. I was an intern working at The Boston Globe, and, when I would return to the office in the afternoon after reporting trips around the city, I had to steel myself for the walk across the sweltering parking lot. As one Globe headline put it — describing the entire city — “Pavement buckles, people lose cool and fans just blow hot air.”

Since then, I have often thought of 1993 as the hottest summer of my life. But it wasn’t, according to historical weather data. It just felt that way because the intensity and frequency of heat was unusual at the time. Today, many of us have become accustomed to heat waves like the one now blanketing the eastern half of the country and much of the Southwest. They feel almost normal.

They’re not normal, however, or at least their frequency is not. As my colleague Manuela Andreoni has written, “2023 was the planet’s warmest year on record and perhaps in the last 100,000 years.” This year may break the record again. Last month was the 12th straight to be the hottest month of its kind on record.

This chart shows the global trend:

In Boston, for example, the temperature reached at least 95 degrees on six different days in 1993. The same has been true in four of the past eight years there. (From the Times archives: See how much hotter your hometown has become.)

Or consider Washington, where I now live. This chart shows the number of days each year that the temperature reached 95. What once qualified as an unusually hot year is now typical: