GRAND RAPIDS, Mich. (WOOD) — There is no question we’ve seen a warm October. Our fall color show is incredibly behind and our overnight lows have been sitting where our day time highs should be.
In fact, this was the warmest start to October on record for overnight lows. Highs have soared into the 60s, 70s and 80s, with lows refusing to dip into the 30s. Keep in mind, we typically begin seeing our first frost across West Michigan over the first few weeks of October.
As of now, October is coming in 11.3° warmer than average. That’s a very large number when we are talking averages, by the way.
DOES A WARM OCTOBER CAUSE A COLDER WINTER?
So does a warm October have any baring on the winter to follow? The short answer is likely “no.”
I did run the numbers from the last 20 years though. I decided to include November and exclude April, since we typically see more snow in November.
The correlation between October temperatures and the following winter is quite low, at only 0.4. When it comes to correlation, the closer the number is to 1 or -1, the more linked the two data sets are. The closer to zero the less linked the two data sets. A correlation number of 0.4 is low.
We should also note that even if the data sets came back as showing a really high correlation, we couldn’t assume that one caused the other.
Here’s a fun example: Say in a particular summer, an area beach sold more ice cream than usual. Let’s say they also experienced more shark attacks. Just because both numbers went up doesn’t mean one caused the other.
WHAT COULD IMPACT OUR WINTER?
One definite factor in our upcoming winter will be the development of the ENSO pattern La Nina. A La Nina pattern exists when cooler than average temperatures begin pooling along the equatorial eastern Pacific. Believe it or not, the water near the equator down in the Pacific Ocean can affect our winter here in West Michigan!
Typically during a La Nina year we see cooler than average temperatures and more precipitation than usual.
The fact that a La Nina has developed this winter will definitely be something we consider when putting together our official winter forecast. There are several other variables that can steer our cold one way or the other.
We will have our full winter forecast launched on Nov. 2, so stay tuned!