I have noticed some apparent changes in the way WU reports "Average" temperatures. Since I like to use AVE temps for analyzing some local weather trends, I would appreciate hearing any acknowledgement, corroboration or verification by others of these observations.

First, though, let me say that I recognize that there are various algorithms for computing average temps.

Type 1: The most traditional (and, unfortunately, least accurate) method is to simply take the average of the daily HIGH and LOW temps. (i.e., AVE = (HIGH + LOW)/2 ) This version is traditional because early analog recording thermometers used to just record daily HIGH's and LOW's, and so the crude formula was the best you could do with the limited data.

Type 2: A better (or at least more physical) way to compute the AVE is to take the integral of all of the day's observations, using the finest sampling available. I prefer this method for my own use, and have been computing this for my own data for many years. As an aside, I have found some interesting data biases that arise when using one form of AVE versus the other, but that is a topic for a different thread.

So, back to WU. It appears to me that WU used to report AVE's using the Type 2 algorithm, or something similar, up to about 2016 or so. Then it appears they switched to the Type 1 algorithm. When I asked them about this back then, I got no response of course. Well, looking at the data posted over the past month or two, it appears that the Type 2 algorithm (or something different still) is back. It is these changes that I would like to hear some acknowledgement about.

I wouldn't be so interested in this if it were not for the fact that the two versions can lead to VERY different values (e.g., up to several degrees on some days -- amounts that swamp any real temp trends). Anyone who is using the data to look at long term trends can't afford to mix the two types of AVE's.

I would be very interested in any direct feedback from WU, or from others who are similarly analyzing the data. thanks all.

Dave G.