I've been studying possible spots to test on this trip and the result is a nice rundown, that I decided to publish to help future "globetrotters". Clicking on the spots listed will give you Windguru's forecast. I'll try to do an updated version, at least with the spots tested, after the trip!
An easy guide to understand the rundown:
***** - Top wind spot, frequently with strong winds
**** - Very good wind spot, with regular wind
*** - Good wind spot, with frequent wind
NORTH COAST:
> Viana do Castelo - 2 exceptional spots, near this beautiful northern city: Cabedelo de Viana (mostly flat and small wave) and Praia de Moledo (flat and wave). *****
> Esposende - Flat on the river side, flat and waves on the beach. ****
> Porto - near the capital of the North, 2 spots are worth the visit: Cabedelo/Foz do Douro (flat and wave, a good spot on the mouth of the Douro river, but the water might be a bit dirty, depending on currents and tides) and Gaia/Canidelo (big wave).
> Espinho/Santa Maria da Feira - the coastal area around the city of Espinho has good waves. Special mention for the Furadouro spot (flat and wave).
> Aveiro - there's a wide range of spots in the area: Ria de Aveiro/Costa Nova (flat on inside waters); on the other side, also on the flat river waters, is the Gafanha spot and, on the ocean side, Praia da Barra (wave). Further inland, there's the Cais do Bico spot, to try flat water kitesurfing among the thin herb bushes. Not very far from there, is Murtosa, highly recommended (****).
> Figueira da Foz - this coastal city has long beaches, with a lot of wave riding potential. Nearby, you can find Berbigão/Ponte dos Arcos (flat on the Mondego river, near a bridge).
Praia da Vieira - a long strip of sand, between Marinha Grande and Leiria. Not very know, it might be worth a try...
> Nazaré - very colourful town, full of fishing history, with a nice wave spot in the north beach (when the swell comes in, it features the biggest waves in all of Portugal, an impressive sight!).
CENTRE:
> Lagoa de Óbidos/Foz do Arelho - flat water in Portugal's biggest lagoon. During high tide it's possible to pass from the lagoon to the ocean, for some wave riding. Restrictions: kiting is forbidden at the end of the lagoon, near the beach, from June 1st until the end of the Summer season. ***
> Ferrel - a "in the middle of nowhere" wave spot, a little further south from Foz do Arelho.
> Peniche e Baleal - a little stop here is almost mandatory, even if it's difficult to have good kiting conditions. Why? Because it has one of the most amazing surfs in the country, on the other side of the peninsula, in Supertubos. You can also check out Baleal's webcam.
> Praia da Areia Branca - a good spot for thermal winds (wave).
> Santa Cruz, Praia Azul and Santa Rita - a sequence of long beaches with easy access and not a lot of kiters around (wave).
> Guincho - A world renowned spot that attracts riders across the world. That said, it's a stop to include in every trip, but the conditions are often only for experienced riders. Winds grow stronger the further you go into the water and there is a big rock in the middle of the spot. On weekends of good conditions, you have to fight for your place in the waves! *****
> Costa da Caparica - the Nova Vaga beach is "the" spot to kite in this long succession of sand strips (and the only one allowed in the Summer season!). If you're looking for a bit of long distance fun, downwind is possible until Fonte da Telha, or even further to the Lagoa de Albufeira.
> Lagoa de Albufeira - flat waters on the lagoon, with possibility to rejoin the waves in high tide. A strong NW winds makes for a great "full speed" session, since you'll have the air on the kite, but the water protected by the sand dunes! ***
> Tróia - before crossing with the ferry, you can find the Figueirinha spot (near Setúbal), that works with south winds. The pretty ferry crossing (you can take your car) takes you to Tróia, where you can find mostly flat spots for almost all wind directions (***). A little bit further south, there´s the Comporta spot, also best with south tendency winds (***).
SOUTH COAST:
> Vila Nova de Milfontes/Porto Covo - a must, for the cool ambiance. In the Praia da Ilha, in front of the Pessegueiro island, you'll find a quiet unexplored spot, possible to navigate between beach and island with favourable winds. For an idea on forecasts, check Zambujeira do Mar.
> Praia da Bordeira/Carrapateira - one of the most beautiful beaches in Portugal! Nice waves and flat when the lagoon forms behind the beach. ***
> Praia do Amado - just a few kilometres south of Bordeira through a dirt road, you'll find this wave spot, with a very "surf roots" feeling.
> Tonel - one of the first spots when turning to Algarve's south facing coast, it offers mid to big waves. Nearby, Martinhal offers regularly strong winds (works with South to East winds; otherwise it's a offshore paradise, but you'll need a security boat to avoid scares!). Tonel and Martinhal are mostly windsurf spots, unless you have a boat to watch over you...
> Lagos - two nice spots to explore here: Meia Praia (on the Lagos bay, it's a flat spot that works with all wind directions) and Alvor (kite on the wetlands, also a flat paradise that works with all winds - ***). Praia do Alvor is also an alternative.
> Vilamoura - a far too touristic place, but with 2 spots worth the try: Praia da Rocha (best with SE winds) and Quinta do Lago (for SW).
> Faro - a lot of potential, in an around the Ilha de Faro (Faro's island). All directions of wind for the flat facing the land and small waves on the ocean side, with SW wind. The Deserta and Culatra islands, reachable by boat (or kite?) offer a nice spot, all to yourself! The Armona island nearby offers flat water and good ocean side kiting with winds from South to East (and you have a camping ground for the night).
> Tavira - the natural park of Ria Formosa offers flat water kiting on a beautiful landscape, but don't forget to respect the restrictions! Ilha de Tavira/Torre d'Aires is a must, offering flat water and small waves. The island and village of Cabanas de Tavira offer a super spot. Best wind is SW, but you can play in the flat water between the mainland and the island with all winds. To cross to the island, you need to get a boat (or, if in a group, try crossing with the kite, while one of your friends takes the rest of the gear!). A personal secret: if your a food lover like me, take the time to drive to nearby Cacela Velha and, near the church, look for a small tavern that offer local seafood specialties (it's not always open, but when it is, you'll get one of the best souvenirs of your trip!).
Hope you find this useful! I stress that this is not supposed to be a comprehensive guide to kite spots in Portugal, but just a rundown of the one's with most potential, in my opinion. If you find others, don't hesitate to tell me, to complete this list!
You can also find more spots in Kitebeaches.com and extra info in the following link (in french!): http://kaf.forum.free.fr/viewtopic.php?t=11526&highlight=portugal
