heat wave topping 100°F set records in multiple European countries this past week. Similar temperatures were also recorded in the United States, including parts of northern China and the middle west.
This is remarkable enough by itself. But what makes them more striking is when they’re happening. As a sobering reminder, it’s not July or August. It’s mid-June. The official start of the summer season is Tuesday.
To illustrate what this early heat looks like in a historical context, we created a chart (below) that compares 25 years’ of daily high temperatures in June and July in Biarritz, a coastal city in southwestern France. As the heat moved through Spain and France, Biarritz was among the hottest cities on Saturday, June 18, hitting a high of 109°F. Prior to this year, the average maximum temperature for June 18 between 1997 and 2021 was 74°F, according to our calculations using historical temperature data from Weather Underground.
Of course, one wildly hot day in a single city doesn’t prove global warming. But such days are becoming more common around the world—and are raising the average temperature patterns overall. What’s more, these heat waves are happening on the fringes of the hot season, causing longer summers with extreme precipitation conditions—both more wet and more dry—around the world. The heat wave season in the U.S. has been extended from just 22 days back in the 1960s, to close to 70 in the most recent decade.
Persistent heat waves are dangerous; Spain and Germany have been battling wildfires amid the scorching temperatures, France canceled outdoor festivities to limit heat exposure over the weekend, and Italy’s health ministry issued health alerts and emergencies for 18 cities between June 22 and June 24.
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Similar alarming conditions can be found on the Atlantic side. The U.S. drought monitor currently shows extreme conditions in the West, which is not only dangerous for heat exposure. The scorching heat is killing cattle, and many states are bracing themselves for power outages. Even hotter nights provide less relief than the oppressive daytime temperatures, which causes average daily temperatures to rise overall, and has a negative impact on human health including sleep loss.
Scott Duncan (London Meteorologist) posted climate commentary and facts on Instagram. A parody video was made by Skeptics, mocking those who dismissed Europe’s heat wave as common summer weather. “We’re breaking all-time records in June. Does that mean nothing?” he asks, sardonically. “It’s never been this hot so early in the year. And we can’t compare this to July and August because it’s just not the same. But you’re quite happy just to call it ‘summer’?”
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