Ok so i had a thought, the jeppesen weather data servers for FSX are still up, which is why FSX still has Real World Weather, if FSX can access them, theres no reason flight gear couldnt be made to use them.
In theory one could either: A: Intercept the data from an open FSX application (the weather is loaded pre flight, but even pre-flight FSX windows take 600MB of RAM, so this may not be practical until we fix the memory issues) or B: Reverse Engineer FSX's extent to figure out exactly how it requests and recieves the data and add a feature using that into Flight Gear, but this would require a great degree of technical skill, and might be illegal in some countrys.