THE data from scientific institutions around the world is pouring in here in the beginning of October, regarding September, 2023, and the consensus is that it was freakishly hot, unprecedentedly torrid, off-the-charts sweltering. It was the Frankenstein’s monster of months.

Much of the extra heat came from human-caused climate change, from our spewing the heat-trapping gas carbon dioxide into the atmosphere to the tune of 40 billion tonnes a year, by burning coal, fossil gas and gasoline. In addition, this is an El Nino year, when the tides in the South Pacific work in such a way as to heat the world up. And, there seem to have been an unusual number of high pressure systems, affecting Japan, German, the US southwest, and Mexico. These may be being caused by a weakened and wobbly jet stream, a result of human-caused climate change.

The Japan Meteorological Agency said in a statement that the average temperature in the month of September in that country was nearly 5°F higher than the September averages recorded 1991–2020. To be exact, the average was 2.66°C or 4.78°F higher.

Remember that this is an average, including mountains and valleys up and down the islands and including both daytime and nighttime. Such a large departure from the previous averages for the month is astonishing for scientists. You don’t expect basic facts like the weather in Japan in September suddenly to deviate by such a large number. Kyodo reports that a JMA spokesperson said, ‘We can’t believe just how high temperatures got. It became a record-breaking phenomenon after multiple factors overlapped on top of climate change.’ The person meant that climate change underlay the spike in temperatures, but that other factors supercharged the heat, including a high pressure system to Japan’s south and the beginning of an El Nino year in the Pacific.

The JMA had already observed of this summer, ‘the average temperature for the Sea of Japan side of eastern and western Japan in early August was… the highest ever. From July 16 to August 23, 106 of 915 observation stations in Japan saw record-high maximum temperatures. The national average surface temperature over summer was the highest since records began in 1898.’

Likewise in Europe, records keep falling. Meteo-France reports that September 2023 is the hottest September ever measured in mainland France since 1900, with an average temperature substantially higher than normal. In the middle of the country, the average temperature was 21.1°C to 21.5°C [about 70°–70.7°F], which puts it in the category of hottest since 1900, ahead of 1949 and 1961, which had also been unusually hot. It was between 6.3°F and about 6.5°F higher than the averages in 1991–2020. In some parts of France it was fully 7.2°F higher than the previous averages.

France 24 points out that ‘Average temperatures in France have been exceeding monthly norms consistently for almost two years.’ A two-year-old toddler in Paris has never experienced a month that wasn’t hotter than the late 20th century averages. A whole new generation is coming, not Gen Z but Gen HOT.

Germany’s Deutscher Wetterdienst reported September to be full of ‘enormous anomalies’ because of a persistent high pressure system, producing a string of unrelievedly sunny days and a lack of rainfall. Summer just rolled on relentlessly, refusing to give way to autumn, as the average temperature through September rose to be 4°C [7.2°F] too hot. The average temperature for the month was about 63°F. According to its website, ‘The extraordinary temperatures in this year’s record September in Germany are further proof that we are in the middle of climate change,’ says Tobias Fuchs, Head of the Climate and Environment Division at the DWD.

In the north German lowlands you had a remarkably high number of hot days with highs of 86°F.

Even cooler England, where the weather was merely in the pleasant 60s F, was nevertheless hotter than it had ever been recorded to be for this month. Back when I was a graduate student in the 1980s I went to Britain in September and it was cool. I was coming from Los Angeles, so I noticed. I remember thinking the beginning of October was like winter. In 1971–2000 the mean temperature for September in the UK was 13.6°C [56.5°F].

For September of this year, the UK Met Office says, ‘England and Wales had their respective warmest September on record according to mean temperature. England’s provisional figure of 16.7°C [62°F] topped the previous record of 16.5°C set in 2006. Wales’ 15.6°C also beat its 2006 figure of 15.2°C.’ And the averages don’t tell the whole story. Heathrow Airport recorded a high of 32.7°C (90.9°F) on September 9, the hottest day of the year so far.

Scott Dance at the Washington Post reports that the average global temperature for September broke previous records by fully half a degree Celsius, which is unprecedented during the over a century we have been recording global temperatures scientifically. You basically had a second July instead of a September.

He quotes climate scientist Zeke Hausfather as calling the September temperature spike ‘absolutely gobsmackingly bananas.’

InformedComment, October 4. Juan Cole is the founder and chief editor of Informed Comment. He is Richard P Mitchell professor of history at the University of Michigan He is author of, among many other books, Muhammad: Prophet of Peace amid the Clash of Empires and The Rubaiyat of Omar Khayyam.