as such, prainha is one of the best options for surf, both on small wave days as well as those with big surf - on this link an early morning shot of the beach is posted daily, showing water conditions.  

the website waves includes charts showing tides, winds, temperatures and overall climate forecasts - containing constantly updated data provided by the brazilian navy, waves is a valuable resource for anyone planning to surf on any beaches in rio.

on this link, the institudo estadual do ambiente - inea, provides the suitability of several beaches, including prainha.