USA: Record high night temperatures in July

A heat wave
Heat wave / Photo: EPA-EFE/ANDY RAIN

The continental United States set a record for overnight heat in July.

July's average low temperature was 17,6 degrees Celsius, beating the 2011 record by several fractions of a degree.

That's not only the warmest overnight average for July, but for any month in the 128 years since record-keeping began, he said. Karin Gleason, a climatologist with the US Oceanic and Atmospheric Administration. The lowest July night temperature was more than 1,7 degrees Celsius above the twentieth century average.

Scientists have long recognized that nighttime temperatures are critical to health.

"When daytime temperatures are at record highs or near record highs and there's no chance of overnight recovery by cooling temperatures, plants, animals and people are under a lot of stress," Gleason said.

In Texas, where the average monthly daytime temperature topped 37,8 degrees Celsius for the first time in July and the power system was under severe pressure, average nighttime temperatures were 23,5 degrees Celsius, 2,2 degrees above the twentieth-century average.

"It warms up faster at night because daytime warming traps more moisture in the air and traps heat at night," Gleason explained.

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