Updated Oct 2, 2023 - Energy & Environment

U.S. Midwest and East say hello to a second summer

Map showing forecast high temperatures on Monday from the National Weather Service. Image: Pivotal Weather.

The sizzling summer of 2023 may be over, but now the U.S. is seeing the reemergence of summer-like heat for tens of millions from Minneapolis to Maine.

The big picture: Temperatures this week have already broken records, including a monthly high of 92°F in Minneapolis on Sunday, which forced the cancellation of the Twin Cities marathon for health reasons.

  • The cause of the heat is a strong ridge of high pressure that has formed out ahead of a plunge of cooler-than-average conditions across the Pacific Northwest.
  • On Sunday, temperatures in the 80s and 90s extended from the Gulf Coast to the northern Plains and Canadian border, which is an unusual occurrence for the beginning of October.
  • Temperatures of 15 to 25-degrees above average for this time of year are expected for the next few days from the Upper Mississippi River Valley and Great Lakes to the East Coast.

Details: This U.S. warmup will be relatively fleeting. Areas stretching from the Northeast into parts of Quebec and Ontario later this week are expected to see the greatest temperature departures from average.

  • Day by day, cooler air will be marching south and east into the Plains and Midwest, courtesy of a cold front that may set off some severe weather as it advances.
  • Cities from Washington, DC, to Boston are likely to be in the upper 70s to low 80s through much of the workweek.

Between the lines: The heat this week comes at the same time as record highs are falling in Europe and Africa, too.

  • A provisional national monthly record was set in Spain on Sunday, with a high of 100.8°F in Montoro, Spain, with record highs also occurring in France and Portugal. It comes as Europe also faces abnormally hot weather, which claimed monthly records on the Iberian Peninsula Sunday.
  • Germany, Austria, Switzerland and Morocco set heat records in recent days, too.

Context: The unseasonable heat follows the planet's hottest summer on record, with the hottest month on record occurring in July.

  • Last month was the hottest September, and October may be on track to set a similar milestone given record warm ocean temperatures worldwide.
  • The blazing start to October in the Northern Hemisphere follows what was almost certainly the warmest September on record for the planet by a large margin.
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