Mauritius is actually always worth a visit. Due to the proximity to the equator, the temperatures are stable during the whole year.
High season is the European winter. Between November and March, the thermometer in Mauritius rarely falls below 20°C even at night, which results in water temperatures of a balmy 26-28°C. However, especially in January and February the chances for cyclones are quite high. However, the hotels of Mauritius are prepared for this and are very safe.
The European summer is the dry season in Mauritius. From April to October there is significantly less rain than in the other months. But with highs of 26-29°C during the day and lows of 17°C at night it never gets cold. Water temperatures stay above 24°C all year round.