Check up on the weather before you travel.  Brazil is a vast country, the size of a continent and the weather can vary massively from one end of the country to the other.  In general the climate is most stable in the North East of Brazil, with average annual temperatures of around 26 degrees Celsius and just a few days of rainfall each year, which usually falls in the low-season months of April-July.  The high season and hottest time of the year is the Brazilian summer period, November-February.