National Data Buoy Centre (NDBC)
This is a site run by the National Oceanic and Atmospheric Admistration (NOAA), and current data for conditions in the area around each data buoy. It also records conditions for the last 24 hours
24 Hour weather forecast, inshore and offshore from the Met Office
No need to say more....
Seems to provide a reasonably accurate 5 day forecast
Well this one is for Sailors & Wind Surfers. But if you look for the days with no stars against them (i.e. low wind) then they should be good for us.
Surf, swell, webcams and much more.
How about this... Going diving in Swanage, then have a look at what the weather is really like now.