OK

This weekend, the weatherman is calling for St.Louis to see snow followed by a decided chill. Sunday night the temperature may drop to -7, making it the coldest in almost 15 years. This has naturally encouraged more than a little chatter along the lines of "how can there be global warming when it's this cold?"  One local radio host has already said that it's clear that there is no warming. After all, it's getting colder!

Only... eh, not so much.

A quick trip to NOAA's  climate archives gives a very different picture than the drive-time commentary. The actual record low temperature for this Sunday's date isn't -7. It's a tooth-rattling -22.

Looking at the temperature records, few trends are immediately obvious. There are high temperatures from the early 1900s. Lows seem scattered around.  But look a little closer.

There are 140 years of records on hand. With 365 days in the year, and 10% of the years in this century, you might expect at least a few coldest days to fall in a year starting with '2.'  If things were actually distributed randomly, you'd actually have better than 30 such chillers. But things aren't distributed randomly. Looking at the month of January, there's not a single record low in this century. February also lacks any record lows from the 21st century. So does March.  

Not one low in winter comes in the last fifteen years.  There are a few chilly spring days, though.  Add it all up, and there are seven low temperature records since 2000—about a fifth what might be expected.

Look at all the record lows, and here's how they fall. Going back to 1874, there was a decidedly chilly period at the end of the 19th century before things settle warmer for the next few decades.  Then things chill through the 1970s (if dad tells you it was colder when he was a kid, believe him). But from there the number of cold days drops. Sharply. The 1990s saw fewer record cold days than any previous decade.  The 2000 saw that low rate cut in half.

So is it going to be cold this weekend? Yep. But not that cold.

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