by Dick Hall-Sizemore
We are used to hearing and seeing weather temperatures reported as being some number of degrees above or below normal. The definition of “normal” has changed this year.
The National Weather Service defines “normal” climate conditions as a 30-year average. New Climate Normals are calculated every 10 years. Before this year, the 30-year time frame was 1981-2010. Now, the “normal” time frame is 1991-2020. As a result, “normal” temperatures have shifted upwards.
Because we are in an era in which climate conditions are shifting, the National Weather Service is adjusting its reporting by providing alternative definitions of “normal.” In response to user groups, it is releasing monthly “Supplemental Temperature Normals.” These reports show averages over 5-, 10-,15-, and 20-year periods, in addition to the traditional 30-year normal. They also show “normal” calculated differently from a straight average. These alternative methods are called “Optional Climate Normal” and the “Hinge Fit.”
Therefore, when it gets hot in the coming months and some folks on this blog, who are not overly concerned about climate change, say that temperatures are not that different from the norm, just remember that normal ain’t what it used to be.