this wundermap shows current temperatures for the various districts in rio de janeiro - the map can also be used to see precipitation, dew point, humidity and visibility. - more weather-related maps are available on this link, and on this link we listed all major events taking place in rio de janeiro in the month of march.  

the instituto nacional de metereologia - inmet  (National Institute of meteorology) provides a wealth of information for all regions of brazil and rio de janeiro state, including Agrometeorology, fire risks, rain maps, satellite imagery, infrared imagery, and statistical databases.