I use Weather Underground and Windy in the states and it does give fairly good BVI readings.
What other sites are good, especially for current & future sea swell conditions?

We find Windguru very accurate.

Another vote for wind guru

My morning weather check (after looking at the sky) starts with WindGuru, it is low-bandwidth and allows for different weather models as well. But I use several sources:

Windy
NOAA
PredictWind (need to register for a free account with an e-mail address)
Zoom Earth
Blitzortung Live Lightning Map ( I use this to see if I'm going to get squalls/storms, it is a really cool app)

I've got a bunch more for hurricane season and detailed weather. But outside of the hurricane season for day sails or passages such as BVI to St. Martin these are all good. But in a pinch, WindGuru will suffice

Note that if you don't have internet, you can still tune your on-board VHF to the NWS weather channel and listen in to the same report that you can get at NWC WXRADIO

I mostly use windguru. They are very accurate 3 days out and ok out to 5 days. I also like this site for swell prediction.

http://www.stormsurfing.com/cgi/display.cgi?a=carib_height

Here's another one:

https://www.ndbc.noaa.gov/data/Forecasts/FZCA52.TJSJ.html

Thanks to all - very helpful!