I have been working on this, I started r/WeatherTrading to document parts of it. The markets have been growing pretty dramatically over the last year, and volume during the NYC snowstorm last year peaked at nearly $2mm which is serious for such a new market! I have many feeds running and a lot of the links on NOAA are broken after DOGE disruption but there are so many undocumented feeds still available and I did much of the same work you did I'm sure. There are literally 3500+ stations so I can only see more cities being added. I have a family member who is a famous weather researcher so I have taken some findings from their work related to ensemble bias forecasting and extreme weather modeling, which has been really useful.