Thanks for that link. It looks interesting. I am a bit worried about their use of personal data (IP address and location), although it wouldn't be an exact location.
Also the 20 requests per second limit was slightly worrying. The app would probably only request weather data once at the start of a workout, so it is unlikely that the limit would be exceeded given the relatively low number of users of WorkOutDoors. However it could possibly be exceeded occasionally (e.g maybe at some race starts).
Generally it looks good, so I will bear it in mind when I eventually look at weather.