March in Cancun is a crazy, beautiful time. The beaches are full of young bodies on Spring Break. Be prepared for crowded bars and night clubs that party until well after daylight.
The weather is all over the place…warm and sunny 85F one day and cold and rainy the next. We have put away our warm blankets 3 times, only to get them back out a few days later.
It is quite windy also. There were many days with strong winds which causes the ports to close. In Cancun there is a port authority that determines when it is too windy to allow boats on the ocean. On windy days your fishing, snorkeling and diving tours will be cancelled.