Mia, hope you have found & read my review now. All the temperatures & wind speeds quoted are from the official cruise log supplied to passengers. You will see that we only had3 days of warm weather in 14 on that section of our trip! If you are going on to Rio you should have extra warm days to us.
You do need a windproof outer garment & layers inside, for the colder areas, see what they are dressed in round Cape Horn in my photos & that was not the coldest part for us! You will however need shorts & tee shirts for the hotter climes