Yes,you will be delighted to know that during the month of September the temperature sits arounds 23-26°C in daytime.And at night ,the minimum temperature goes around 15-17°C .
In the month of September,the temperature is much cooler and for the most of days,you will not even have to use the Room air conditioners.Moreover it rains less.Even,the best time to travel to the mountainous part of Mauritius is from September to early November.