Although, Florianopolis does not face a conventional four season climate, yet it is better to exercise a little precaution depending on what month you are planning to visit.
Hot Season (December- March): The temperature during these four months shifts from a comfortable 20 Degree Celsius to 30 Degree Celsius. The weather is quite pleasant and is actually the best time to visit Florianopolis to enjoy the city completely.
Rainy Season (June- September): The city experiences rainfall over 100 mm during these months. Although during July, the rain is not that high. But rest of the months, it is better to be prepared for rains at all times.
There are no chilly winters as such but it is better to carry a sweater with you at all times from April to December as such.
April and May are quite pleasant with April being the driest month. January is generally the hottest month with temperature maintaining a 30 degree Celsius average. September is the wettest month. A windcheater, an umbrella, a sweater is enough to protect you from the rainfall or the winters.