Heat Wave???

We're having an "unseasonably" warm spell this week, with temperatures in the 60s. It was 66 yesterday, one degree shy of the record for January 30th.  I was discussing the weather with one of my foreign born co-workers, who has only been in the area for a few years. He asked if this kind of warm spell was unheard of. I suggested that while 60's is certainly above average, I believe warm (or could) spells are actually quite normal, and to be expected. Further I suspected that there's been a day at least 60 in just about every January.

Well, my blanket statement got me thinking, and I decided to do some research. Looking at Climatological data for St. Louis, going back to 1874, the record high temperature for each day in January is 65 degrees or above. The year for when the record high occurred varies from 1876 through 2012, and the record highs vary between 65 degrees and 77 degrees.  Naturally, I put the data in a graph, covering the entire winter season (Dec 21 through March 20):

I find it interesting just how wide the range of actual measure temperatures is. In the context of a “normal” temperature of 41, yesterday’s 66 seems dramatic. But 66 degrees falls within the historic range, so it's not exactly stunning.  Over the past 138 years, the high temperature on January 30th has been between 67 and as 10 degrees.

But what of the original supposition? Looking at the data, January did not have a 60 degree day in either 2011 nor 2011. BUT, every year from 2001 through 2009 did. That’s 80% of the last 10 Januaries have seen temperatures above 60 degrees in January. Not every, but certainly most….