The Riviera Maya has two broad seasons. The dry season runs from November through April — warm, sunny, and reliably calm, with temperatures in the low-to-mid 20s Celsius. This is peak tourist season and prices are higher, but conditions for diving, snorkelling, and cenote swimming are at their best.
The wet season from May through October brings afternoon thunderstorms and higher humidity, but mornings are often clear and the crowds thin considerably. Hurricane season peaks between August and October; direct hits are infrequent but storms to the north and south can bring rough seas and closures at dive sites.
The whale shark aggregation off Cancún and Isla Mujeres runs roughly from June through August — accessible as a day trip from Puerto Aventuras. The reef fishing is generally better in the dry season for marlin and sailfish; the summer months bring more dorado (mahi-mahi).
Cenote conditions are consistent year-round — the underground water is always clear and cool.