Mauritius weather in may

Beach, Mauritius, originally uploaded by Markus Hillius.

May is a great time to visit Mauritius. You can expect that the overnight minimum temperatures will range between 19-21°C and by day, you should see temperatures up to 27-28°C. It certainly won't be cold but nor will it be really hot.
that's when winter starts to come in. This is the "cold" season there which is PERFECT weather if you come from outside the tropics. i.e. live in uk or usa. the summer (december) "hot" part of the year is actually almost too hot unless you are aclimated to tropical weather.

It's a known fact that both the western and northern regions of Mauritius record the highest temperatures and also receive less rain than any other part of Mauritius and so if I was you, I would check out a beach in these areas.

If you want to have minimal worries about the rain, then keep away from the south eastern part of Mauritious since shower activity combined with the gusty south easterly winds can make life miserable at the beach around this area in the afternoon.

If you plan to go surfing then check out Tamarin beach. Another popular beach for young people (not for surfing though) is Pereybere.