September temperatures in W. MI trending warmer

GRAND RAPIDS, Mich. (WOOD) — Have you noticed it? Warmer Septembers.

I’ve noticed over the years the public’s curiosity as to whether or not Septembers have been warmer. The map below confirms the suspicion that, more often than not, Septembers have become an extension of summer.

The map was created by Brian Brettschneider and shows what months out of a calendar year that have warmed the most during the past 30 years.

The most prominent has been September (yellow), encompassing the vast majority of the eastern U.S. We can also see why snowbirds head south during the winter.

I thought it would be interesting to rewind and crunch the numbers from the past 30 Septembers. Here’s what I got:

Nearly two-thirds of them have been warmer than average. The warmest years in that stretch were 2007 with +5.3 degrees, 1998 with +5.1 degrees and 2005 with +5.1 degrees.

Combining all of them, September temperatures have been running 1.4 degrees above average.

In fact, just three years ago we cooked through one of Michigan’s most prolific heat waves. Between Sept. 21 and Sept. 26, we sweated through six consecutive days with record-setting temperatures exceeding 90 degrees. The record high temperature on the 23rd exceeded the previous record by a whopping six degrees.

The duration of this heatwave was only surpassed by March 2012 and July 1936. Both those years tallied seven consecutive record-setting days.

Like the rest of 2020, this September has not followed the script so far. Temperatures have been running a little over 3 degrees below average with only a couple of days exceeding 80.

This week will achieve above average temperatures as the jet stream position will be positioned north of Michigan through Saturday. This will allow the warmth to push northward as well.

The pattern change arrives next week as the jet stream carves out a deep trough across the Great Lakes and eastern half of the country. This airmass appears cold enough to generate some lake effect rain showers and may be even a few waterspouts.

This should also bring us highs in the 50s for the first time this season.

The 8-14 day temperature outlook indicates the cool temperatures may stick around through the first week of October. Note that the average high is only in the mid-60s during this time frame.

Hopefully, the cooler and wetter pattern won’t dull the fall colors. Stay tuned to future reports through the season.