Suggestion for 1:1 ratio line in daily temperature normals plots

[ahuang11]

I think it would be beneficial to add a translucent, perhaps dotted, 1:1 ratio line which can highlight that Houston is generally warmer than San Diego most of the time.

(Please excuse this poor edit done in Paint)

[clauswilke]

That's not an important point of the figure in the context where it appears. It would simply make the figure busier and more complicated to explain.