September could be among the warmest ever in metro Detroit history

Posted at 12:26 PM, Sep 25, 2017
and last updated 2017-09-25 16:41:01-04

While the month of September has been warm, the last week has been scorching. When the high heat and humidity finally breaks, we will have had almost a full week of near  90 degree weather.

With our typical September high temperatures sinking through the 70s, this heat has been the talk of the town. It has also lead to speculation about what this means for winter.

I have taken a look at other really warm Septembers, searching for clues about the months ahead. And while we will no doubt have our share of frigid winter nights and cold, blustery days, this warm September may foretell warmer than average winter temperatures.

So far, this month has had an average temperature of 67 degrees. With two additional days of near 90 degree weather (Monday and Tuesday) and another 80 degree day this month (Wednesday), we will likely make the list of warmest Septembers on record in Detroit. (We'll probably place somewhere between 17th and 20th on the list.)

Looking at the current top 20 warmest Septembers on record, I compared them to a list of the top 20 warmest winters for Detroit. The results were encouraging.

Six of the top 20 warmest Septembers were followed by a top 20 warmest winter! This is fully 1/3. This does not include winters that were warmer than average, but not in the top 20. So there is a good chance, though not a guarantee, we'll have a warmer than average winter if the September signal is to be believed.
In fact, five of the eight warmest winters had a top 20 warmest September! Conversely, none of the top 20 warmest Septembers were followed by one of the top 20 coldest winters.
A look at the temperature outlook for October-November-December reflect the likelihood of warmer than average weather holding. We are in the 40% chance of above-average temperatures during this timeframe.

Stretching this out to look at December-January-February, we have equal chances of above average and below average temperatures.

Given the signal an unusually warm September seems to send, the equal chances of a warmer than average winter seems like a bet many would be willing to take.