Timing your visit.
Brazil is basically on holiday from Christmas until after Carnival, for this reason travel is expensive and frustrating between late December and early March. All holiday destinations are crowded and accommodation difficult to find unless booked well in advance. Ubatuba has a population of 70,000, during the holiday season this swells to 250,000!
The best time to visit Ubatuba is the spring and early summer, September to early November, the birds are in song and resplendent in their breeding plumage; however any time of year can be good bird-wise here.
The temperature on the coast in winter sometimes falls below 10ºC and in summer it can rise to the high 30's. The summer has frequent afternoon rain which brings the temperature down. Most rain falls in the summer, but because of its proximity to the Serra do Mar there is always a chance of rain, sometimes heavy.
Mornings can be cold, particularly at Campos do Jordão, which is at high altitude and can experience freezing temperatures in the winter.