Found a couple of low-res images
of both Sirius'
Seems that the Bahamas the Dominican Republic
are in fringe areas, and perhaps Puerto Rico
and the USVI are just on the bleeding edge. You might need a very good high-gain antenna
to pull in the weak signal.
While having weather overlays right on your chartplotter
are nice, Gord and Vasco are right - when the chips are down, there's always HF radio
"BLOS" (what we who work in darker circles call Beyond Line Of Sight
What we plan on doing when we take off in Beausoleil this fall is to get GRIB files delivered via WinLink or Sailmail when not near civilization, and to just download them via WiFi
when we are. We have a Raymarine E-120, but the weather overlay function in Maptech's Chart Navigator Pro are nicer...