There are several amazing beaches in Setúbal, Sintra and Cascais that can be visited between May and October every year.
Portugal is home to some of the most beautiful beaches in Europe. Some people think they need to travel all the way down to the Algarve region to visit hidden paradises in the summertime, but these can be also found within a one hour radius by car from Lisbon.
Either by exploring the wonders of the Parque Natural da Arrábida ("Arrábida Natural Park") or by chasing the sun at the Parque Natural de Sintra-Cascais ("Sintra-Cascais Natural Park"), well-preserved wild beaches are easily reacheble departing from Lisbon. This is our recommended list of paradisiacal beaches very close to Portugal's capital and, therefore, accessible in a simple day-trip:
1) Praia do Ribeiro do Cavalo, Sesimbra, Setúbal;
2) Praia de Galapinhos, Setúbal, Setúbal;
3) Praia da Ursa, Sintra, Lisbon;
4) Praia de Santa Marta, Cascais, Lisbon;
5) Praia do Magoito, Sintra, Lisbon.
Go check out my guide for the best free things to do as well as itineraries and travel tips to make your trip unforgettable.