I use an Iridium phone and Zygrib, which is a free weather
program that I highly recommend. You can choose what files you download so that you can keep file sizes low. Zygrib allows you to send an email
to their server to request a return email
with grib files attached.
I use spsmail.net for all satellite
email, which uses protocols especially for low bandwith/ high cost connections that reduce minute consumption
considerably, and found that I can get the necessary grib files for a 3 day forecast
at about 30 kb, which is about a minute of download time. Don't ever try to download your yahoo or gmail email over a sat phone. Will take forever and may never finish.