At long, merciful last, the northern plateau’s Scorching September has come to a close. And, as it does, September 2019 will go on record as perhaps the most miserable September in Oneida’s history.
September 2019 ended with an average temperature of 72.3 degrees in Oneida — enough to edge out September 1970 (71.6 degrees) for the second-warmest September ever, but not quite enough to top September 2018’s record-setting warmth, when the average temperature was 73.4 degrees.
However, the back-to-back Septembers of 2018 and 2019 were warm for entirely different reasons. September 2018 set a record as the warmest month of September ever in Oneida because nighttime temperatures stayed consistently muggy, due to an abundance of moisture over the region. A total of 12.21 inches of rain fell in Oneida during the month, smashing the old record of 8.89 inches of September rainfall, set in 2003. In fact, September is typically the second-driest month of the year on the northern plateau, but September 2018 featured more rainfall than the typical months of May and December — the two wettest months of the year — combined.
So while September 2018 featured hotter-than-average daytime highs, it was barely hot enough to break the Top 10 hottest Septembers in that category.
By contrast, September 2019 was not about an abundance of moisture, but a lack of it. With total rainfall for the month measured at just under four-tenths of an inch, it was the second-driest September on record.
The abnormal dryness allowed radiational cooling to drive down temperatures at night, which prevented September 2019 from catching September 2018 in overall warmth.
But September 2019 was in a league of its own when it came to daily high temperatures. With eight days featuring temperatures climbing into the 90s, September 2019’s average daily high temperature was 87.8 degrees. That makes 2019 the hottest September on record in that category, beating the old record of 1998, when the average daily high was 86.7 degrees.
That means Oneida has experienced back-to-back record-hot Septembers, for different reasons.
Even though nighttime temperatures were lower in September 2019 than in September 2018, they weren’t exceptionally so. In fact, temps dropped into the 40s just one time last month. Prior to 2018, there had never been a September with fewer than two nights in the 40s, and that had happened just a handful of times — 2009, 2005, 1978, 1973 and 1971. The average for the month is eight nights with temperatures in the 40s. But in 2018, not a single night was recorded with temps dropping below 50 degrees, and it happened just once in 2019.
It appears the heat will finally break by the end of this week. And while above-average temperatures are still likely, it will at least start to feel a bit more like fall.
History can’t tell us too much about what to expect for October after an exceptionally hot September. The results are muddled.
In 1998, which featured the second hottest September temperatures, the warmth continued into October, which was one of the five hottest Octobers on record in Scott County. But in 2005, which featured the third hottest September temperatures, October’s temperatures were slightly below normal. Other years with exceptional September heat that lingered into October were 2016, 1973 and 2007. Years that saw the heat break for a pleasant October included 2002, 1980 and 2018.
For what it’s worth, NOAA’s Climate Prediction Center is forecasting the above-average temperatures to continue throughout October.