Almost every big city tries to capitalize on that fact and organize an off-season carnival. Fortaleza has Fortal, Recife has Recifolia, Brasilia (a city famous not just for not having carnival, but also for not having any other means of having fun) has Candango; Natal has Carnatal.
Carnatal takes place sometime in early November. It has happened in the streets around Machadao (traffic around the stadium changes radically during Carnatal days), but every year a discussion arises about the convenience of moving the party somewhere else (people who live around that area claim they pay too much tax and are unhappy with all the noise that Carnatal makes).
While in Rio it's difficult (though possible) for foreigners to participate directly of the parades (most tourists just watch alegories passing by), in Carnatal participation is the norm.
There are several "blocos", which consistly basicly of a famous band playing music very loudly on the top of a big adapted truck; the truck moves slowly along the streets, and the members of the block are allowed to follow it, singing, dancing and enjoying themselves (plenty of drinking, flerting, hugging, kissing). A membership costs around R$100, and you are identified by a characteristic t-shirt, called abada; only people wearing abadas can follow the block.
You can also just watch the blocks; either you pay a small fee to be allowed in the cabines mounted around the Carnatal streets, or just wander around for free.

