When to go to Ubatuba
The worse traffic you get is on holidays, fridays and sundays, for obvious reasons. A lot of Brazilians love Ubatuba, many of them have houses here, so, every weekend a lot of people comes and goes from here. On Friday after work, and Sunday after lunch there's always some traffic. If the holiday is on Friday or Monday it gets worse.
If it's Friday or holiday; come late at night with an experienced driver.
October to April we have warm and hot weather (min. +24ºC max +36°C)
May to September we have chilling and cold (min +14°C max +27ºC)
What to pack
As you saw above, it depends on which season are you coming to.
Just consider that: more sun, hot weather, more rains. We have the ocean and a huge mountain the other side, sometimes blocking the clouds.