Open Mind

This summer (June/July/August) was America’s hottest on record, at an average temperature of 74.7 °F:

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I monitor climate-related data, including the total wildfire area burned in the USA according to the National Interagency Fire Center (NIFC). Here’s the yearly total acres burned since 1983 (the figure for 2026 is year-so-far):

The straight-line fit (by least squares regression) reveals an upward trend which is certainly statistically significant. I hear reports from credible sources saying that the year-so-far figure for 2026, almost 8 million acres, is about 170% of the average on this date over the last 10 years.

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I’m prepared to predict, even two weeks before it’s over, that summer 2026 will end up as England’s hottest on record.

Central England Temperature (CET, data available here) records the average temperature over a large region of central England, starting on January 1st, 1772, and includes both daily high and overnight low temperatures since 1878. What does it have to say about summer heat? Here’s the summer average (June/July/August) for daily high temperature:

The upward trend recently is plainly evident. The final value, for 2026, is hottest of all, but will change as new data arrive. When “the smoke clears” it is overwhelmingly likely it will still exceed any previous year.

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Until recently, the hottest month on record for USA48 (a.k.a. the “lower 48 states” of the USA) was July 1936, with two of the five hottest months from the 1930s (the “dust bowl” era). Not any more. According to data from NOAA, we just set a new record; now the hottest of all is July 2026, and four of the five hottest are after the year 2000. In the following graph, this July is circled in red:

Perhaps of greater interest, at least scientifically, is the trend in USA48 temperature, which is clear from yearly average temperature anomaly (the last value is year-to-date for 2026):

The average warming rate since 1975 is 0.31 ± 0.09 °C/decade (0.56 ± 0.16 °F/decade, intervals are ± 2σ), which is more than 50% larger than the global average rate.

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The forest in Canada is burning, and the smoke is a big problem for both Canadians and Americans as it makes its way across their country and into ours. Our president has blamed Canada for mismanaging their forests and threatens to hold them responsible, but the truth is:

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The Berkeley Earth surface temperature project provides monhly averages of high temperature, and high temperature anomaly (how different it is from “nominal”), on an equal-area grid over all the land areas on Earth. I computed, for each year and for each grid, the summer high-temperature anomaly as an indicator of just how hot each summer was, for each grid. So far, I’ve only done the northern hemisphere extratropics, so this is a report on summer (June/July/August) heat for land areas north of latitude 23°, an area which is home to much of the world’s population.

I surveyed the results to identify the year, and the summertime anomaly, of the hottest summer for each grid. Here’s a map showing which grids peaked before the year 2000 in blue, and those which peaked after 2000 in red, with the size of the dots indicating how intense the hottest summer was.

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Most of the world shows a notable, and statistically significant, rise in extreme summer heat. That’s not an opinion, it’s a fact. The reason is: global warming. That’s a fact. The consequences include a lot of unnecessary deaths, a tremendous financial cost to cope with the heat, and massive financial loss from reduced productivity. Each year it costs tens of thousands of lives and billions of dollars, and that’s a fact.

When it comes to this year’s heat waves, the focus has been on western Europe. There are numerous indexes of how heat wave intensity has changed from year to year (I’ve developed a few of my own), but one of the most easy-to-use and easy-to-acquire is simply to calculate, for each year, the average daily-high-temperature anomaly during the summer months (June, July, and August). It’s not a perfect measure, but is a surprisingly good one, and in Europe, temperature records extend far enough back in time to give us good estimates of just that quantity over more than 200 years.

For France, I acquired such data from the Berkeley Earth surface temperature project, but it only extends up to the year 2018 so I supplemented it with ERA5 data, covering the time span from 1950 through 2025. Here’s what they say about summer average high-temperature anomaly in France:

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