I have a couple of Raspberry powered weather station near Prato, Italy.
The software running them is SWPI, an open source project developed by a local hang gliding pilot, it outputs a meteo.txt file with json formatting, but i guess it could be tweaked to meet any kind of api.
I'd surely be happy to share my data with everybody for free, even if some kind of "Windy contributor" gadget would definitely be cool 😁

I have the same issue with OnePlus One / CM13, i am available for testing, if you need