Weather will likely play an important role when you plan your trip to Santa Catarina, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and May, with an average temperature of 21°C, while the coldest months are January and December, with an average of 16°C. The rainiest months in Santa Catarina are September, June, August and July, with each month seeing an average of 258 mm of rainfall.