What Fall? How Historically Hot Has September Been


Today is the first day of fall, but so far, this September has been significantly hotter than the average July or August.

The average Middle Tennessee August ticks off ten days with a daily high of 90 degrees, according to the Weather Underground’s compiled historic data. (They use National Weather Service data that reaches back to the 1800s.) Usually, the hottest days of the average year here are July 30 through August 10, which all average a high of 90 degrees. On either side of that the average high falls to 89 (F) for a few weeks or so before moving lower- from late June through late July averages 89 (F) as a high; as do mid- through late- August. Readings are taken at the Nashville International Airport.

Overall, August historically is the hottest month of the year here. July averages two days with a high of 90 degrees; August averages 10; September none.

Since the first 90-degree day this year on May 11, the mercury broke 90 degrees (F) on 81 of the following 131 days. That is more than seven times more than “normal.” May had five, June had 19, July had 22, August had 24.

And September? 11 so far.

In fact, two-thirds of the way into the month, the average daily high temperature for this sultry September is exactly 90 degrees. The normal average high for September, through its first 20 days, is 84.3 degrees, starting at 87 degrees in the early half and steadily cooling down to 81 degrees by the 20th.

Moreover, temperatures on all but three days this month surpassed the average, by as much as 11 degrees – last Friday with a high of 93 degrees, had a historical high of 82 degrees.

This is no surprise, given that last year, according to NASA, NOAA and the UN, was the hottest year not just recorded but probably in thousands of years. And the same agencies say that so far 2016 has been even warmer.

On Tuesday, NOAA released a climate report that showed the hottest summer on record just ended. Global temperatures peaked at 1.6 degrees Fahrenheit above average, 60.1 degrees from June to August.

According to the report, global warming from human activities and the end of the moderating El Niño cycle combined to push temperatures up.