There's nothing like an all-inclusive holiday in Celestún to revive you, especially when you know what to expect from the elements. Here's some information to help you decide when to book: The hottest months are usually May and July, with an average temperature of 28°C, while the coldest months are January and February, with an average of 24°C. February and March are the driest months, while June and September are the rainiest months.