You're right, VHF is not useful once you get 100 or so miles at sea.
There is lots of wheather info available, however. If you google something like "offshore high seas weather broadcasts" you'll find lots of sites with good information.
The USCG voice broadcasts weather info for many high seas areas several times a day.
The weather products are shown on this site:
The frequencies and schedules of broadcasts are on this site:
Weather services of several European countries (e.g. UK, Germany) also broadcast forecasts for the high seas and offshore areas closer to Europe. You can find information on these on the internet via google.
As SailingDog mentioned above you'll need a HF (high frequency) receiver to monitor these reports and others on the HF bands.
"Southbound II" mentioned in SD's post above is an excellent source of personalized weather information. Herb Hilgenberg (call sign "Southbound II") talks with boats in the North Atlantic and Caribbean every day year round. He begins his roll call at 2000 Z on (if memory serves) 12,359 KHz. Once you check in with Herb he'll give you a forecast for your specific area and routing recommendations every day for the length of your voyage. He doesn't charge for this service -- and because of the quality of his work and his long service to the yachting community he's held in high regard by all who know him. He does have his own way of doing things and you need to play by his rules -- but it's a small price to pay for the information, guidance and assistance he renders to all who call upon him.
There are other sources of weather information available if you have an amateur radio (HAM) licence. The Maritime Mobile Service Net (when last I checked they were on daily on 14300 KHz) will relay weather information they get from NOAA and other sources on the internet. If you check in with them with your current position, someone will find the forecast for your area and read it to you.
If you get a SSB (single side band) radio and have a laptop with appropriate software you can receive in facsimile form USCG broadcasts of NOAA weather charts several times a day. You can see the content of these broadcasts for the North Atlantic region at
Surf around the page above, especially in the links immediately above the weather charts for information on the products, schedules and frequencies.
Last, if you have budget for it, you can get customized weather forecasts for private weather services (e.g. Commanders Weather) for $30-40/day. They'll send your forecast by email, or talk to you on a sat phone -- but both of these require additional hardware, and the cost will mount very quickly.
Hope this helps.