When I released UNHIDING THE DECLINE three days ago, I mentioned that there were probably bugs in it. I found one which is causing it to report recent temperatures too cool.
NOAA has lost a lot of station data since 1990, and a number of these missing data entries have been showing up in the .dly files as “7-9999.” I was looking for “-9999” but did not recognize “7-9999” as being two separate fields. Because of recent NOAA station data loss, this was causing me to calculate post-1990 temperatures too cool.
Please update your code! ghcn.py for Linux/Mac ghcn.exe for Windows
These are the correct graphs for summer temperature.