Heat waves broke records on 2 continents before the start of summer

Two extraordinary heat waves sent temperatures soaring into uncharted territory in Europe and the United States ahead of the summer solstice, setting new benchmarks for the month of June in several European countries.

Why is this important: Extreme early-season heat is a development meteorologists call “disturbing” and “unprecedentedThese events are a clear wake-up call to the growing influence of global warming on day-to-day weather.

  • Heat waves are deceptively deadly, with heat-related illnesses striking the most vulnerable among us, from the homeless to the elderly, to the poorest residents who cannot afford the air conditioner.
  • Such events are particularly dangerous when they occur in late spring or early summer, before people are accustomed to high temperatures.
Earth surface temperatures detected by the Sentinel-3A and Sentinel-3B satellites on June 19, 2022. Image: Platform Adam.

The big picture: The jet stream, which is a fast-flowing river of air flowing east to west at high altitudes in the Northern Hemisphere, connects the two continental heatwaves via an atmospheric wave pattern. Over the past week the jet stream across Europe and North America has been dominated by strong high pressure ridges, also called heat domes.

  • In Europe, the heat wave began weeks ago as warm air accumulated over North Africa. This air mass eventually made its way north into Spain. Aided by a highly amplified jet stream installation, the heat then swept over France and central Europe.
  • A persistent area of ​​low pressure centered west of Portugal helped pull warm air north through its counterclockwise airflow.
  • Across the United States, the jet stream has been twisted like a snake, with the heat dome currently centered in the middle of the country. Temperatures in the Midwest are expected to hit triple digits on Tuesday.

Enlarge: Human-caused global warming changes the background conditions under which extreme heat events occur, and some studies suggest it also affects the jet stream itself.

By the numbers: The heat in Europe and the United States has not been your typical hot summer weather, in fact temperatures would be unusual for mid-summer, let alone mid-June. National June heat records were set in Switzerland, Poland and the Czech Republic over the weekend.

Sea surface temperatures in the Mediterranean.
Sea surface temperature anomalies in the Mediterranean Sea. (European Union, Copernicus Marine Environment Monitoring Service)

Heat wave has helped raise water temperatures in the Mediterranean to 9°F above average, depriving southern European coastal areas of heat relief and potentially harming marine life.

Meanwhile… In the United States, record temperatures weren’t as scorching as in Europe, but the heat was relentless.

  • 101°F: High temperature Monday in Minneapolis, breaking a daily record.
  • 2,074: Number of hot temperature records set or tied, including daily highs and lows, in the lower 48 states during the seven-day period ending June 17, compared to only 444 cold records during the same period, according to NOAA.
  • 22: Number of all-time hot temperature records set or tied during the seven-day period ending June 17, compared to zero all-time cool temperature record during the same period.

And after: As Europe takes a break from the heat, the Midwest and South will see temperatures soar to dangerously hot levels this week, before extreme heat slides west along the Gulf Coast into the Texas. The National Weather Service describes Tuesday’s conditions as “sweltering heat and humidity” with temperatures 15-25°F above average in some areas.

  • With drought in control of Texas and most of the West, it’s likely that more bouts of record-breaking extreme heat are in store for the summer season.

Go further: The heat wave will migrate from the Midwest to the south this week