Porto's Sá Carneiro Airport (OPO) is only about 15 minutes from the heart of the city of Póvoa de Varzim and is served by a rail line of Porto Metro that ends at the airport.
Trains leave about every 20 minuties throughout the day and all head to Porto centre. To reach Póvoa, you must catch a new metro in Verdes station (just two minutes, or two stations away), and use the eastern most platform of that station and wait for a line B metro, all of them have terminus in Póvoa de Varzim station. there are four metros each hour, one of those is 'Expresso', it means it doesn't stop in several stations, meaning that a trip to Póvoa is faster. Trip from Verdes station take 32 minutes and by 'Expresso' it takes only 23. In the airport you must buy an Andante rechargeable fair (50 cents). To travel to Póvoa de Varzim you must charge it with 3 zones that will cost you just around 1 euro.
By car, you can reach the city from Vigo in Spain or Porto using the toll-free A28 Motorway. The city also has other motorways linking it to other interesting near-by cities, to travel to or from Guimarães one should use the A7, to or from Braga you should use the A11. A11 and A7 have intersections in the A28.
By the sea, Póvoa de Varzim is one of the Portuguese maritime borders, there's a Marina and a seaport in Póvoa. Coordinates: 41°22′N, 8°46′W
There are buses that regularly link the city to/from Porto, Galicia, shuttle buses to/from Lisbon and there are also the Euroline - the European wide-bus service. All use the Central de Camionagem, the central bus station of the city, close to the beach area. And there are city mini-buses from Litoral Norte that you can catch to head to another places or you can also use another bus systems (such as Linhares) to travel around the city or the countryside.