Worse than that garbage excuse, is that what they told you is for the AN (the newest radio model that we can't even get in our vehicles).
OUR VEHICLES DON'T HAVE A WEATHER APP - IN FACT NO APPS AT ALL!!
You need to have a conversation with the management at your dealership. The advisor is an idiot.
In the meantime they will need to replace your radio in any case . . . . if they can't get a replacement from FCA immediately tell them to pull one from a vehicle on the lot. They can take one from any Journey, Charger or 300 with the option. If they won't, then they can provide you with a comparable loaner vehicle, since it is obvious that you require functional navigation as a critical feature necessary to your use of the vehicle.
And, if you plan to keep the vehicle and haven't bought it already, I strongly suggest you consider buying an OEM extended warranty - perhaps from a dealer that knows what it is doing.