Would you be able to find a workaround for the offline issue?
For example a "Print Report" option that generates a PDF that we can use after we lost connection.
This is a common feature in websites like Met Office.
In that way you won't be exporting the data but "visualising" it on "paper" (PDF).
Other people suggested a video recording feature. A snapshot friendly screen... Or you may even be able to generate images of weather maps and/or forecasts.
It should to be a work around... At the moment the only option are screenshots or printing the forecast before leaving home... Not ideal.
Please could you make an effort in this sense?
Your app is awesome and I am pretty sure people will be willing to pay for features like this.
All the best!