Bloemfontein: Annual Weather Averages. January is the hottest month in Bloemfontein with an average temperature of 23°C (73°F) and the coldest is June at 8°C (46°F) with the most daily sunshine hours at 9 in October. The wettest month is February with an average of 130mm of rain.anuary is the hottest month in Bloemfontein with an average temperature of 23°C (73°F) and the coldest is June at 8°C (46°F) with the most daily sunshine hours at 9 in October.