This is an excellent and comprehensive article about visiting Porto. 

When the rain lashes in off the Atlantic to a soundtrack of gulls cawing, Porto’s betrayal of its Latin latitude feels at its strongest. There’s a sense of misplaced northern Europe about Portugal’s second-largest city, particularly in the winter months when the ocean roars in with crashing swells.

Source: Porto: Fine wine and understated charm in Portugal’s Latin city with northern soul | Europe | Travel | The Independent