The relative humidity for Punta Cana in October ranges between a mildly humid 65% and a very humid 95%, rarely dropping below 55% or reaching 100%. The air is most often at its driest around October 4 th, when the relative humidity levels drop below 70% three days out of every four.ctober 5 th is usually when the air is at its most humid, when the relative humidity levels exceed 92% three days out of every four. The average sea temperature for Punta Cana in October is 29°C – that’s the same as in August and September.