French marinas will normally post fabulously detailed forecasts for several days ahead in the harbour office. Unfortunately, they're sometimes fabulously wrong. Spanish marinas are much the same but maybe not so conscientous about updating. I found the navtex gives as good a forecast as anything
Obtain Admiralty Nautical Publication NP289 from your marina swindlery (in stock last time I looked), it gives all the Navtex transmission information UK & Med and points in between as well as all the marina & harbour info as well.