I have hesitated to discuss California temperatures until I had tools in place to analyze it properly, and I do now. NOAA shows maximum temperatures in California rising rapidly, and particularly a big jump after 2012.
The actual average maximum thermometer data shows no net change over the past century prior to 2012, but a big jump over the past six years. (I excluded Death Valley from this analysis, because they started reporting in the 1960’s and cause a fake long term warming bias on the right side of the graph.)
However, something is seriously wrong. There are 53 USHCN stations in California, and only nine show warming since 2012, but thirty-one stations show cooling since 2012. Whatever is causing the post-2012 spike is not real. It must be something along the lines of cooler stations not reporting as many days as the warmer stations. I haven’t figured it out yet, but am quite certain that whatever is causing the recent spike in temperature is a data artifact.
Additionally, there are quite a few California stations which show long term cooling in their afternoon temperatures.
I no longer see any reason to believe California is warming.