I notice that the dashboard interface for the Historic Charts (interface/js/chartshistoric.js) has a commented-out doWindDir() routine which reads data from api/dailygraphdata/winddata.json.
Is the API that this code talks to still under development, hence the routine being commented-out? Out of interest, I un-commented it and created a button in chartshistoric.html to call it, but although the axes are drawn, the graph hangs on "Loading". If the API isn't there, that probably explains it
Is the intention that there will be daily dominant wind direction readings, with the same time values (UNIX epoch times for DD/MM/YYYY 00:00:00) as for Max Wind, Max Gust and Wind Run in the doWind() routine?
Is there a reason why you are using a separate json file / API rather than adding it to api/dailygraphdata/wdirdata.json that is read in doWind(). It would be useful to plot Dominant Wind Dir alongside Max Wind, Max Gust and Wind Run on the same time axis, which is a lot easier if all the data is in one json file than trying to merge data from two different files.
I may be barking up completely the wrong tree here. I hope you'll forgive me my curiosity