Do you mean a list of observation types, eg outside temperature, inside temperature, rainfall, wind speed etc? If so that is very much dependent on the driver/station you are using. If you are using one of the drivers distributed with WeeWX then you may find some useful information for each driver/station in the WeeWX
Hardware Guide, in particular the Station Data section at the end of each driver section. For example, here is the vantage driver
Station Data section for the Davis Vantage stations. If you are using a third party driver you need to refer to the driver documentation or the driver author.
Or are you referring to the tags used in WeeWX reports? (this would not seem to be something you would normally document on a PWS web page but each to his own). If you are, then again there is no definitive list, you will find some information on the type of tags supported in WeeWX reports in the
Tags section of
The Cheetah generator section of the
Customization guide, but this really only covers the type of tags available; ie current data, aggregates of historical data etc. Again the driver/station determines what observational data (outside temperature, wind speed, rainfall etc) is available.