Here is the design of the latest data field I'll develop over the next few days as I have time.
The Toybox.Weather API is nice, in theory. If you've played with that, does it work reasonably well? I assume it requires your smartphone to be in cell tower range, and Garmin Connect Mobile to be running and connected to your Garmin device?
There isn't a way to calculate the altitude of the weather reporting station, right? So an adjustment could be estimated for temp (say you are 3000 ft above the station's elevation).