Use proxy with Forecastie
You can download a modified version of forecastie with an option to set server manually in settings. For my server go to settings, select custom server and input "https://trafficpixel.tk".
You can download this version here or compile it youself using "git clone github.com/erdmark/forecastie.git" and "gradlew.bat assemble" or "gradle assemble" depending on your environment.
If your phone is routed you can also change dns with the hosts file:
Download AdAway , Options->Hosts sources->add https://trafficpixel.tk/data/adawayOWM.txt
apply ad blocking (this sets api.openweathermap.org to point to my server at 126.96.36.199)
source code is here