Climate is mostly tropical, but temperate in south.
For the experienced surfers, Brazilian winter is the best travel season, because there are generally bigger waves (up to 8 feet from June to August)
The winter brings stormy weather while the Summer afternoon thunderstorms. Deep winter can be surprisingly cold. The water remains stable all year round, but a steamer is definitely required for the winter.
Reflecting conditions of its geographical location in a sub-tropical latitude, and under a pleasant marine influence, the climate of Santa Catarina island is characterised by its moderate thermal range, annually 8.8 o c and daily, 4.2 o c. The summers are hot, not quite reaching 40 o c/104 o f and the winters are mild, never reaching 0 o c/32 o f or below.
According to the Köppen classification, Santa Catarina is located in a mild humid climate region, with hot summers and rain uniformly distributed throughout the year. For Edmon Nimer the thermal variations make the most notable difference in the climate of the southern region of Brazil. According to Nimer the island has a mild climate where the average low temperatures during the year are between 15 - 18C. According to the Strahler classification, Santa Catarina Island has a humid climate with an accentuated dominion of the Atlantic Tropical Maritime Air Mass during the year.
The climate of the region is controlled by the predominant action of the Intertropical (hot) and Polar (cold) air masses that determine its mild character. Outstanding as the dominant system of local circulation the Tropical Atlantic Mass (TAM) with 80% of action and the Polar Atlantic Mass (PAM) with 20%. The TAM acts throughout the year, but is more noticeable in the spring and summer, while the PAM acts more frequently in the Autumn and Winter months. There is, apart from these two predominant systems, the Atlantic Polar Front which is the result of the contact of the TAM with the PAM and causes the rains in the region that, on the island, are pre-frontal, frontal and post-frontal.
The advance and retreat of these air masses also determine the temperature. The advance of the TAM, known by its North, Northeast, and Northwest winds, from its origin of the semi-fixed subtropical Atlantic anti-cyclone, provokes a rise in temperature. While it remains imobile it transforms the region into a centre of low pressure, raising the temperatures even higher. The mass has a high humidity due to its maritime origin and the high temperatures amplify the humidity level. With the advance of the PAM and its contact with TAM, a region of frontal discontinuity, called the Atlantic Polar Front, is formed provoking periods of rain.
The PAM which has its origins in the high latitudes of the Southern Hemisphere, is identified by the South and Southeast winds, frequent in the Autumn and Winter months. The predominance of this air mass and its Northward movement cause stable weather and low temperatures, known in the region as cold waves.