published by Instituto Estadual do Patrimônio Cultural - INEPAC (the State Institute of Cultural Heritage), through the Secretaria de Patrimônio Cultural (rio's Cultural Heritage Department), this link shows a calendar of cultural events throughout the year.

furthermore, the link can be used to find out about cultural events for specific dates throughout rio de janeiro state, by selecting a city in the drop down menu.  

the site Boa Diversão publishes a constantly updated list of upcoming events, including a variety of minor and always fun sporting events, artistic events, and shows.