Add my vote for export to MySQL (not SQLite). That would include all data from extra sensors too.
I created a database schema for MySQL and used the Custom CGI option to invoke a PHP page to insert records into the database. Quite simple. The huge downside is that it floods my web logs even though I'm only using a 60 second timer. For large web sites, that would get lost in the noise. For a home web site, it's the dominant entry.
Since the Custom CGI also uses GET instead of POST, each log entry is huge. I suppose I could figure out how to configure Apache to have a separate virtual web server with its own custom log file, and I may still do that, but having native support for MySQL would be much preferable. If weather monitoring isn't perfectly suited for data gathering and retrieval, I don't know what is.
One of the main reasons I want a searchable database is that the current web page creation does not allow PHP, or AJAX to query the data. We have to hardcode the date ranges of values in the PHP page, it gets variable substitution by WC and then the PHP executes. Too late to dynamically calculate and request a range of data.
I want to build an AJAX web page that allows me to view data using a JQuery slider to dynamically display ranges of data. I simply can't do that without a searchable database.
Anyway, if you do embark upon this task then there should probably be a public discussion on the data schema. While I'm no database expert, I have become somewhat opinionated over the years.
Thanks for listening.