One of the highlights of late autumn in the Barcelona area is without doubt the Festa Major de Sant Andreu de Palomar, which in 2018 is celebrated between 28th November to 9th December.
Although I haven't seen it advertised this year, there is normally a traditional fun fair along Carrer de Sant Adrià next to Can Fabra.
Most events take place in Plaça Can Fabra but Plaça Orfila, Plça del Comerça and the Ramblas Fabra i Puig and Onze de Setembre are also important locations as are the smaller streets of the Casc Antic and venues such as L'Harmonia and the Centre Civic.
The botifarrades and menjars populars (street food) are always good in Sant Andreu and with such a vibrant community life you also get some of the best Gegants, Diables, Trabucaires and Tamborers in Catalonia so you should definitely check out the Cercavila or Main Procession on Sunday November 27th as well as the Correfoc, of course.
There's also the Festa Alternativa with alternative music and events, who normally have a tent in Plaça Can Fabra.
In order not to miss out on the wide range of activities, family events, performances and concerts, you can consult the Full Programme on the Official Festa Major de Sant Andreu de Palomar website.