http://platformio.org/platformio-ide
There you can install libraries directly via console command in the IDE.
Find libs here http://platformio.org/lib and install for example: > platformio lib install 13 to install Adafruit GFX library (not needed...) Then you need some hosting space, for the server-side script which parses data for Wemos D1 mini. It's a tiny PHP script. If you don't have any hosting space, you can register for any of the free hosting services. You'll also need to fill in Wunderground API key (free registration needed) and location ID in the PHP source file on the server. The PHP script is in directory server-script. Copy it to server for example with Filezilla client.