It's thirty-five point seven degrees. The hottest month in Sanya is June, with an average temperature of 28-5 degrees Celsius and an extreme maximum temperature of 35-7 degrees Celsius. In July, the average daily temperature in Sanya gradually decreased, from 28-5 degrees Celsius in June to 28-3 degrees Celsius. In August, the average daily temperature in Sanya dropped from 16 to below 28- 1 Celsius. In September, the average daily temperature in Sanya dropped.