Howdy!
Seems that I am not the only one with the same problem.
I am having the same issue.. AND it seems that you and I have the same thing happen and it started at the same time!
around 3 pm on the 29 May.
I frankly think that it is something to do with WUnderground.
Previously I noticed that the temp rapid fire readings would change and the "other" t1, t2 temps would flash up under "current conditions".
This has been doing this for as long as I can remember. But these would never translate to recorded readings.
I wonder if it has something to do with how the site was set up originally and now
WU is making changes to how it accepts data[size=78%].[/size]At any rate I don't have time to look into it till the weekend.
If you do manage to fix it please let me know.
https://www.wunderground.com/personal-weather-station/dashboard?ID=IONTARIO891#historySylvester