They are not going from Canary, but from Azores, that are 750 nautical miles to the North.
There is a famous Transat race that at the first and second weeks of November passes near Azores. Almost in every edition they experiment strong winds and many times big storms when they pass in that area. On the 2002 edition 3 60ft racing cats capsized there and they had already their sails down. I know that a cruising cat is not a racing cat, but come on, a 36 ft cat on winds over 70K and huge seas? Would you risk a fair possibility of encountering those conditions?
I know they original post said the Azores, however checking the Azores page on wiki there is no Gran Canaria shown in the Azores. On a tourism page for the Azores, they lump the Azores, Maderia and the Canaries all together so this may be where the confusion comes from. Anyone with any sense would sail south and pick up the trades to cross, adding only 5 days or so to the trip. Also the first and second weeks of Nov are just at the end of the storm season which may be why they are hitting those conditions.
And actually anytime you go offshore you risk encountering storm conditions it is just the nature of the business.
Does anyone know if there is a Gran Canaria in the Azores or perhaps the original poster can clarify if they are leaving fron the Azores proper or Gran Canaria in the Canaries.