Weather will likely play an important role when you plan your trip to Diamantina, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October, with an average temperature of 21°C, while the coldest months are July and August, with an average of 17°C. The rainiest months in Diamantina are December, November, January and March, with each month seeing an average of 276 mm of rainfall.