First week of September has been hot, keeping with climate trends

We’re already 7 days into September and it’s been a very warm start. September is one of our fastest warming months in Minnesota.

Fall warming

Fall overall is a fast warming season in Minnesota as well as the southwest and northeast portions of the United States. If you’ve noticed that summer seems to persist longer into autumn, you’re not just imagining it.

In the Twin Cities, September average temperatures have warmed nearly 6 degrees in the past five decades alone. Overall, September average temperatures have warmed more than a whole standard deviation over a century.

Cool nights are arriving later

One of the most noticeable climate trends across Minnesota are warmer nights. In the Twin Cities the average date of the first night cooler than 50 degrees now comes more than two weeks later than it used to, in mid September.

The first frost since the year 2000 has averaged around October 16, compared to October 4 in the 1960s and 1970s. In the most recent decade, that average first frost date is October 20. While most places outside the Twin Cities see an earlier frost, away from the urban heat island, the trends are similar. Growing seasons are getting longer.

A hot Thursday before rain, cool air

Speaking of warmth, Thursday will bring one more hot day. Many places will be near 90 in southern Minnesota along with muggy dew points in the 60s to near 70.

Showers develop Thursday night into Friday and Friday night along with cooler temperatures. High temperatures will be in just the 60s and low 70s this weekend. There are indications of summer temps, possibly above 80, returning by the middle of next week.