Karina,
I don't think ANY of the weather apps mentioned work "offline", i.e. with no cellular coverage.?
Have you looked at asking for a "Premium Weather Forecast" from your InReach?
See here:?
Here is a separate free weather service for InReach that works by you sending a message to a specific address and receiving back a message with a shortened forecast:
Another one I found is OCENS SpotCast, which is not free.? Never tried it.? The responses seem difficult to interpret in my opinion.