Wisconsin experienced the third warmest September on record

The Wisconsin state climatologist said preliminary data shows last month was the third warmest September on record.

At the beginning of September, parts of the state were experiencing highs in the mid- to upper-80s, which are between five and 15 degrees higher than normal. Near Boscobel Airport on Sept. 15, the temperature rose to 92 degrees. 

“It was a very weird September,” Steve Vavrus told WPR’s “Wisconsin Today.”  He added it was also among the 10 driest, with data going back to the 1890s. 

The trend is happening across the Midwest as neighboring Minnesota logged its warmest September since the state started keeping track in 1873. 

Vavrus is also a senior scientist in the Nelson Institute for Environmental Studies Center for Climatic Research and co-directs the Wisconsin Initiative on Climate Change Impacts.

He recently joined WPR’s “Wisconsin Today” to talk about the strange weather patterns. 

Rob Ferrett: Why was the weather so unusual this September?

Steve Vavrus: It is a combination of factors. One long-term factor, of course, is a warming climate. All of our seasons are getting warmer so a warm September in that sense isn’t unusual.

But the magnitude of this was certainly unusual, and a lot of that was caused by a circulation pattern that was very favorable for warm, dry weather. We had an unusually persistent high pressure located in eastern Canada and that was blocking the rain-bearing weather systems that normally move in here. 

It was also drawing down dry air into Wisconsin, in the upper Midwest, much like last summer’s drought pattern.

RF: What are some of the consequences with these abnormally warm days through the fall?

SV: One thing that’s become a concern around Wisconsin is drought. It was not on our radar at all earlier in the summer when we were overly soggy, but since then there’s been a gradual drying trend and it was really accentuated in September. 

Now in the northern half of the state, drought has really emerged. In fact, severe drought has now been classified for Northeast Wisconsin. Some places up there haven’t received any significant rainfall in over a month. 

RF: How problematic is the unusual weather for farmers? 

SV: In many ways this September has been favorable for farming. It’s certainly good for harvesting. It’s been so dry we haven’t contended with early frosts. 

But this heightened risk of fire is very real and that’s a concern for farmers. In the big picture, we’re seeing more of this boom or bust precipitation cycle. 

Going back to last year, we started with record wetness the first few months and then we had a major drought. This year, we started with a drought and then got really wet with record flooding, and now we’re back to drought again. This is very hard for anyone to plan for, including farmers, and it appears that this is probably one symptom of climate change.