Minnesota just had its warmest fall on record, and it wasn't even close
If you’re keeping track, we had the warmest September on record statewide and in the Twin Cities. What's more, it wasn’t remotely close, and it follows on the heels of last winter being the warmest on record by far.
We’re now wrapping up meteorological fall, which runs September 1 through November 30. The consistency of the anomalous warmth has been remarkable. It wasn’t just a really warm September but every single week essentially of fall has been, with just a few, brief shots of cooler weather.
In the Twin Cities we’re likely to beat the previous #1 fall (1931) by a whole degree Fahrenheit.
Six of the top 10 warmest falls in the Twin Cities have happened since 2011.
So, despite the last 14 years making up just 8% of our 151 year dataset, it’s over-represented by 6 to 7 times. This is a key figure that consistently stands out. When we look at a top 10 or 15 warmest months or season, the modern years are way over-represented.
Statewide data crunching takes longer, but there’s really no reason to think 2024 won’t also be record warmest for all of Minnesota. Temperatures anomalies are running +5 to +7 deg F above normal across all of Minnesota with no exception.
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The thing left to watch for the remainder of the last weeks of this year are where we’ll rank for the entire year, big picture. Depending on November’s final average temperature numbers, we’re neck and neck with 2012 for the warmest year to date. In 2012, December was about +1.7 deg F above normal.
If this year’s December is less than that, which is very possible given La Niña conditions, we may fall short for the year. BUT, Decembers have been overall pretty warm in recent years – even in La Niña episodes. The big trend is that even in a normal or cooler winter, winters are starting later, which bumps up December average temperatures.
Only five of the past 15 Decembers have been cooler than the modern average (1991-2020) of 21.7 degrees in the Twin Cities. The modern normal is a full 2 degrees warmer than the historic December average temperature.
Regardless of the final outcome, a simple statistical analysis shows that this year, despite a strong El Niño to start, was made virtually impossible without man-made climate change warming annual average temperatures a full 3.4 deg F since the first half of the 20th century.
The standard deviation of annual average temperature is just 2 degrees, so that’s an absolutely huge amount of warming on an average basis. Of course, in the Twin Cities some of this is the urban heat island too, but that is also a man-made change and one of the things that cities around the world should look at to reduce the further warmth of urban bubbles. Simple solutions like more vegetation, green roofs, different paved materials, etc. can all help drastically on that front.
BMTN Note: Weather events in isolation can't always be pinned on climate change, but the broader trend of increasingly severe weather and record-breaking extremes seen in Minnesota and across the globe can be attributed directly to the rapidly warming climate caused by human activity. The IPCC has warned that Earth is "firmly on track toward an unlivable world," and says greenhouse gas emissions must be halved by 2030 in order to limit warming to 1.5C, which would prevent the most catastrophic effects on humankind. You can read more here.
