the month of may in rio is classified by brazilians as autumn, though by north american or european standards this means something entirely different - temperatures generally tend to stay between of 18 and 27 degrees celsius, with the temperature dropping gradually throughout the month.

the month sees gradually falling daily high temperatures, with daily highs averaging around 26 degrees celsius, at times exceeding 32 and  dropping below 21 - daily low temperatures range from 18 celsius to 20 celsius, rarely falling below 16 degrees.   

a trip to the beach during this month is certainly still viable, especially during the hotter hours of mid-day - between one and three pm or so.