Majorca: Annual Weather Averages. August is the hottest month in Majorca with an average temperature of 25°C (76°F) and the coldest is January at 10°C (50°F) with the most daily sunshine hours at 13 in July.The wettest month is October with an average of 69mm of rain.The best month to swim in the sea is in August when the average sea temperature is 26°C (79°F).he wettest month is October with an average of 69mm of rain. The best month to swim in the sea is in August when the average sea temperature is 26°C (79°F).